List of characters in mythology novels by Rick Riordan
This is a list of characters that appear in the Camp Half-Blood Chronicles, The Kane Chronicles, and Magnus Chase and the Gods of Asgard.
Overview
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- A dark grey cell indicates that the character was not in the property or that the character's presence in the property has yet to be announced.
- A Main indicates a character had a starring role in the property.
- A Recurring indicates the character appeared in two or more times within the property.
- A Guest indicates the character appeared once in the property.
''Camp Half-Blood Chronicles''
Introduced in ''Percy Jackson and the Olympians''
Percy Jackson
Percy Jackson is a demigod, son of mortal Sally Jackson and the Greek God of the sea, Poseidon. Percy lives in the Upper East Side of Manhattan and is a New York Yankees fan, but found his life uprooted upon discovering his true paternity. He has black hair and sea-green eyes. He has inherited special abilities from Poseidon which include the ability to control water, boats, and ships; to create small hurricanes; to breathe and see clearly underwater; and to talk to horse-like creatures and most aquatic animals. He is also a gifted swordsman using his shape-shifting sword pen. Throughout the series, Percy uses a ballpoint pen named Anaklusmos for battle; the pen can change into a celestial bronze sword and if he loses it, it will always appear back in his pocket. His fatal flaw is Loyalty.His mortal life was not the best. He, like all demigods, was diagnosed with ADHD and Dyslexia. This made him the subject of bullying from his peers. Additionally, His mother was once married to Gabe Ugliano, an abusive, gambling addicted, alcoholic in order to protect Percy. His repugnant mortal odor masked Percy's demigod scent, hiding him from monsters. At the end of The Lightning Thief, Sally turned Gabe into stone using Medusa's head. Later, she married Paul Blofis, for whom she has genuine love. Percy also find love at the end of The Last Olympian with his long time friend Annabeth Chase.
Percy is the first-person narrator in the Percy Jackson & the Olympians series. He appears in The Lightning Thief, The Sea of Monsters, The Titan's Curse, The Battle of the Labyrinth, The Last Olympian, The Son of Neptune, The Mark of Athena, The House of Hades, The Blood of Olympus, The Hidden Oracle and The Son of Sobek. In the films, he is portrayed by Logan Lerman. In the musical, he is portrayed by Chris McCarrell.
Grover Underwood
Grover Underwood is a satyr and Percy's best friend. He appears in The Lightning Thief, The Sea of Monsters, The Titan's Curse, The Battle of the Labyrinth, The Last Olympian, The Son of Neptune, The House of Hades, The Blood of Olympus and The Burning Maze.He has curly reddish-brown hair and fur, acne, and a wispy goatee. His horns grow larger as the series progresses, and he must take increasingly careful measures to hide them and his goat legs while posing as a human. In The Lightning Thief, Chiron states that Grover is small even for his age: He is twenty-eight then, but because a satyr's lifespan is twice that of a human, he is considered a teenager. Grover is quite sensitive and attached to nature. A vegetarian, he is known to eat tin cans, furniture, and worships cheese enchiladas. Like all satyrs, he can sense emotions and "smell" monsters and demigods. As the series progresses, his concern for his friends and the pursuit of his goals leads him to take on leadership roles and become more confident. Unlike his demigod friends, Grover is not an orthodox fighter. Instead, he uses reed pipes or a cudgel. In The Battle of the Labyrinth, Grover begins a relationship with the dryad Juniper.
In The Lightning Thief, he gets a "searcher's license" after delivering Percy safely, allowing him to search for the lost god Pan. When Polyphemus captures him in The Sea of Monsters, he activates an empathy link, a psychic bond with Percy created a year before, allowing them some telepathic communication across great distances. He uses this to guide Percy to his rescue. At the end of The Last Olympian, he is named a Lord of the Wild and given a seat on the satyrs' ruling council, the Council of Cloven Elders.
Annabeth Chase
Annabeth Chase is the daughter of Athena and history professor Frederick Chase. She has an extensive paternal family including Magnus Chase. In The Last Olympian, she and Percy start a romantic relationship. She appears in The Lightning Thief, The Sea of Monsters, The Titan's Curse, The Battle of the Labyrinth, The Last Olympian, The Lost Hero, The Son of Neptune, The Mark of Athena, The House of Hades and The Blood of Olympus. In the film adaptations, she is portrayed by Alexandra Daddario. In the musical, she is portrayed by Kristin Stokes. She is described by her teacher Chiron as "territorial about her friends", which is manifested in some moments of jealousy and distrust. In The Lightning Thief, it is revealed that she also suffers from arachnophobia, a fear shared by her siblings due to their mother's relationship with Arachne, whom Athena turned into a spider. She has had a crush on Percy Jackson ever since he arrived at camp.Annabeth ran away from her father and stepfamily at age seven and encountered Luke Castellan and Thalia Grace. They lived as runaways until they were found by Grover Underwood and taken to Camp Half-Blood. Annabeth remains attached to Luke and convinced of his goodness even after his decision to support Kronos. Her attempts to bring Luke back into the fold are an important theme in the books. A crucial character to the series' arc, Annabeth even spends some time in Tartarus with Percy and Bob the Titan during The House of Hades. At the end of the series, she and Percy plan to finish high school in New York and then attend college in New Rome. In The Hidden Oracle, Percy states that Annabeth had gone to Boston for "some family emergency" — searching for her cousin Magnus Chase. Annabeth's appearances in crossover shorts with The Kane Chronicles, and in Magnus Chase and the Gods of Asgard make her the only character besides Percy Jackson to have appeared in all three of the Greco-Roman, Egyptian, and Norse mythology series by author Rick Riordan.
Her main weapon is a short celestial bronze knife given to her by Luke. After losing it in The House of Hades, she uses a drakon-bone sword given to her by the giant Damasen. She also uses Sadie Kane's wand when it turned into a dagger like the one Luke gave her. Annabeth also owns an invisibility Yankees cap, a gift from her mother. At the end of The Battle of the Labyrinth, Daedalus gives Annabeth his incredibly advanced laptop which she loses in Tartarus. In the third book of Magnus Chase series, Annabeth wears a UC Berkeley College of Environmental Design shirt, implying that is where she goes to college. Annabeth has dyslexia, as her brain is hardwired to be able to read Ancient Greek, and has ADHD.
Luke Castellan
Luke Castellan was a 19-year-old son of Hermes and May Castellan. He appears in The Lightning Thief, The Sea of Monsters, The Titan's Curse, The Battle of the Labyrinth and The Last Olympian. In the films, he is portrayed by Jake Abel. In the musical, he is portrayed by James Hayden Rodriguez.Introduced initially as the friendly head counsellor of the Hermes cabin, Luke is soon revealed to serve Kronos. He is resentful of his father, who adhered to the gods' policy of non-interference despite May Castellan's mental illness. He ran away from home at a young age and eventually arrived at camp. After the loss of Thalia, a failed quest and continued silence from Hermes, his ongoing resentment turned into a strong hatred of his father and the other gods. Described as decent and kind before Kronos, he behaved with volatility and violence after his defection. Though Luke originally served Kronos willingly, the horrors he witnesses during the Battle of Manhattan convinced him to fight against his former master, eventually committing suicide to stop the [|Titan]. When he died, Luke reiterates what Ethan Nakamura told Percy earlier: unclaimed children and unrecognized gods deserve more respect than they have been given. Percy later fulfills his request.
Luke is described as handsome with sandy hair, blue eyes, and a long scar on his cheek given to him by Ladon. Besides the ability to open locks with his mind, inherited from his father, he is first and foremost an excellent swordsman. He even receives a sword named "Backbiter" from Kronos at the end of The Lightning Thief. It is later reforged as Kronos's scythe and has the ability to harm both mortals and immortals. From Halcyon Green, he receives a diary he later entrusts to Chiron, and a celestial bronze knife he later gives to Annabeth with a promise to always remain her family. From his father he receives a pair of magic flying shoes, which he later curses and gives to Percy. Just before giving himself over completely to host the spirit of Kronos, Luke bathes in the River Styx and obtains the invincibility of Achilles.
Thalia Grace
Thalia Grace is the daughter of Zeus and Beryl Grace, a TV starlet. She is seven years older than her brother Jason Grace and appears in The Lightning Thief, The Sea of Monsters, The Titan's Curse, The Last Olympian, The Lost Hero,The Blood of Olympus, The Dark Prophecy and The Tyrant’s Tomb. In the films, she is portrayed by Paloma Kwiatkowski.Due to her mother's abusive nature, Thalia had considered leaving home since she was little, but stayed to protect Jason. When Jason is seemingly killed during a visit to Sonora, Thalia finally ran away and stayed with Luke and Annabeth until they met Grover when she was 12. When they reached camp, Hades sent a horde of hell hounds that Thalia held off, sacrificing herself for her friends. Zeus pitied his daughter and turns her into a pine tree where her spirit then provides a magical barrier around the camp. Seven years later, she is purged from the pine tree with the Golden Fleece, applied to save it from poisons that were weakening and destroying the wards protecting the demigods. At the end of The Titan's Curse, she becomes the lieutenant of the Hunters of Artemis, a band of immortal female archers who serve the goddess Artemis, which freezes her age the night before her 16th birthday.
Thalia has blue eyes, spiky black hair, black eyeliner and punk style clothing. Annabeth and Chiron remark her personality and character traits being very similar to Percy's. She also shares some traits with her father, such as his pride, confidence, and vehement reactions to betrayal or contradiction. An incredibly skilled warrior, she is willing to attack even Luke, who was known as the best swordsman of the last 300 years. Thalia's weapons are the shield Aegis disguised as a silver bracelet, and a spear disguised as a Mace can. After The Titan's Curse, she also uses a bow and hunting knives. Her main power is the ability to summon lightning and generate electric shocks. In The Titan's Curse, it is revealed that she has a rather ironic fear of heights, acrophobia. In The Lost Hero, she embraces Jason for the first time in years, only to learn that he had lost his memory.
Tyson
In The Sea of Monsters, Tyson is introduced as Percy's bullied, childish friend. When Percy is forced to take him to camp, it is revealed that he is a baby Cyclops and thus a son of Poseidon, making him Percy's half brother. He appears in The Sea of Monsters, The Titan's Curse, The Battle of the Labyrinth, The Last Olympian, The Son of Neptune, The Mark of Athena and The Blood of Olympus. In the films, he is portrayed by Douglas Smith.Tyson is tall with unkempt teeth and fingernails, brown hair and eye. He is mentally about 8 years old, but very intelligent and compassionate. As a son of Poseidon, he shares some of Percy's powers. As a Cyclops, he is immune to fire and has super strength, an uncanny ability to mimic voices, enhanced senses, and understands the "old tongue". Tyson also becomes an excellent smith with help from Charles Beckendorf. In The Last Olympian, he proves himself to be a capable fighter and is named a general of Poseidon's armies. Percy is at first resentful of him as a brother, while Annabeth is openly hostile towards him because she was almost killed by a cyclops, but both accept him after their quest together in the Sea of Monsters. Tyson is close with several characters and magical creatures in the series, including Rainbow the hippocampus, the hellhound Mrs O'Leary and the harpy Ella, who eventually becomes his girlfriend. In The Battle of the Labyrinth, Tyson is revealed to be afraid of satyrs, including Grover, he manages to conquer this fear after a quest and they become friends.
Nico Di Angelo
Nico Di Angelo is first seen in The Titan's Curse, as an unclaimed demigod rescued by Percy, Annabeth, Thalia, and Grover. At the end of the novel, it is revealed that Nico is a son of Hades. He appears in The Titan's Curse, The Battle of the Labyrinth, The Last Olympian, The Son of Neptune, The Mark of Athena, The House of Hades, The Blood of Olympus and The Hidden Oracle.The character Nico was named after one of Riordan's former students.
Though he appears to be ten years old, he and his elder sister Bianca were born in the 1930s. After Zeus killed their mother Maria, daughter of an Italian diplomat, whilst trying to kill the children, Hades wiped their memories and placed them in the Lotus Hotel, a place in Las Vegas where time stands still. He is a native of Venice and can speak Italian. Nico is initially depicted as cheerful and childish, with olive skin and dark hair, and enjoys playing Mythomagic. He takes the death of Bianca very hard, becoming moody, secretive, and irritable. He becomes angry at Percy, who swore to protect Bianca, but later forgives him. Afterwards, he lived in the Underworld with Hades, where he becomes pale and shaggy-haired and begins wearing dark clothing. Nico, despite being very powerful, is extremely lonely, much like his father. He makes nearby people uncomfortable, partially due to his unnerving weapon of choice: a sword made of iron cooled in the Styx, capable of absorbing monsters' essences rather than banishing them to Tartarus. Until meeting Cupid in The House of Hades, Nico also struggles hiding his homosexuality. During The Blood of Olympus, Nico, Reyna and Hedge transport the Athena Parthenos to Camp Half-Blood. Between The Blood of Olympus and The Hidden Oracle, he begins a relationship with Will Solace, a child of Apollo, after admitting to Percy that he had a crush on him.
Nico's suggestion that Percy takes on the curse of Achilles and his work to convince Hades to fight in The Last Olympian is crucial to the Olympians' success and earn him a short bout of fame. He is privy to the fact that there were two camps, one Greek and one Roman, before The Lost Hero, making him an important liaison between the two groups in the latter series. He brings his half sister Hazel back from the dead and establishes her at Camp Jupiter. At the end of The Son of Neptune, Nico travels through Tartarus to find the monstrous side of the Doors of Death, an experience which leaves him haunted and weak. In The Blood of Olympus, he nearly dies several times while "shadow-traveling", which involves melting into shadows and teleporting himself to different places. His sister whom he brought back from the dead, who goes by the name Hazel Levesque, is the daughter of Hades' Roman identity Pluto.
In The Hidden Oracle, Will Solace introduces him as his boyfriend to Apollo. Although their attraction for each other is hinted in The Blood of Olympus, they are not seen getting together. After the three-legged death race, he is seen assisting Will treat the injured patients. At the end of the book, he helps Apollo and the others fight after he and Will's canoe capsized.
Rachel Elizabeth Dare
Rachel is a mortal girl who can see through the Mist, the force that obscures gods and monsters from most mortals. Her father, Will Dare, is a rich businessman, a fact which she is rather adverse to. She first meets Percy in The Titan's Curse at the Hoover Dam. In The Battle of the Labyrinth, she guides Annabeth and Percy through the Labyrinth to Daedalus's workshop. It is hinted that she has some romantic feelings for Percy which are noticed by Annabeth who becomes jealous. In The Last Olympian, she has strange visions and becomes the new Oracle of Delphi. Her first act as the Oracle is to deliver the next Great Prophecy, setting the plot of the Heroes of Olympus series. She is contacted by Annabeth in The House of Hades to ask for Reyna's assistance to bring the Athena Parthenos back to Camp Half-Blood.Following the loss of Delphi to Python, as revealed in The Hidden Oracle, Rachel stops visiting camp and begins a frenzied attempt to regain her foresight, not helped by Apollo's disappearance. Once informed of Apollo's arrival, Rachel returns and learns that not only Delphi is lost, but also three other Oracles, and that only Rhea's Dodonian Oracle is still valid. She becomes upset upon learning of the existence of other Oracles, as Apollo hasn't told her before.
She has red hair and freckles, is skilled at painting and drawing and occasionally shown as a non-ADHD foil for her demigod teammates. Percy remarks on her ability to stand still for a long time at a charity event. Due to her power of foresight, Rachel knows a great deal of knowledge before she learns it herself, during her meeting with Reyna, she states Reyna's full name, something only Reyna's best friends know.
Clarisse La Rue
A daughter of Ares and the former lead counsellor of the Ares cabin at Camp Half-Blood, Clarisse is hot-tempered, courageous, strong, an incredible fighter, usually using an electric spear given to her by Ares, and a good military strategist. She can be stubborn and overconfident, much like her father. Despite their similarities, Clarisse has a fear of her father and his anger at her if she should ever disappoint him. This, along with a strong sense of honor and pride, often motivates her actions. She also fears the Labyrinth because of what happened to her boyfriend Chris Rodriguez before she saved him. She is aggressive towards most demigods, including Percy, though she does respect and make friends with a few, including Percy, Annabeth, and Silena Beauregard.Clarisse makes frequent appearances throughout the novels. first seen just after Percy arrives at camp. In The Sea of Monsters, Clarisse is given the quest to find the Golden Fleece. She is a main character in the short story "Percy Jackson and the Stolen Chariot". In The Last Olympian, Clarisse initially sits out the war for Olympus due to a personal feud. Enraged after the loss of her friend Silena, she later joins the battle with a fury reminiscent of her father's, slaying a drakon singlehandedly and receiving the blessing of Ares. In The Blood of Olympus, Clarisse leads the Greeks in battle to defend the camp. In The Hidden Oracle, it is stated that Clarisse has gone to attend the University of Arizona and her role as counsellor is taken by her half-brother Sherman Yang.
She appears in The Lightning Thief, The Sea of Monsters, The Battle of the Labyrinth, The Last Olympian, The Mark of Athena, The House of Hades and The Blood of Olympus. In the film adaptations, she is portrayed by Leven Rambin. In the musical, she is portrayed by Sarah Beth Pfeifer.
Calypso
Calypso is the daughter of the titan Atlas who is imprisoned on the island of Ogygia for supporting her father during the first titan war. She first appears in The Battle of the Labyrinth, where she nurses Percy back to health. She falls in love with Percy and is heartbroken when he has to leave. Percy asks the gods to release her at the end of The Last Olympian, but she is still residing there when Leo becomes trapped on Ogygia in The House of Hades, having been released from the curse of being forced to fall in love with all those to fall upon the island rather than the island itself. Leo and Calypso subsequently fall in love legitimately. After Leo escapes, he swears on the River Styx that he will return for Calypso. At the end of The Blood of Olympus, Leo gets back to Ogygia and frees Calypso although nobody can go to Ogygia twice.In The Hidden Oracle, Calypso comes to Camp Half-Blood with Leo and reveals that, due to her choice to leave Ogygia, she has become a mortal. She accompanies Leo and Apollo in the latter's quest to find the Oracles and stop the Three Emperors from conquering North America. Despite this, the two secretly attempt to find a normalcy for their lives and later announce to Apollo that they are going to settle in Indianapolis, although they will continue to help him anyway they can. At the end of The Dark Prophecy, Calypso stays at the Waystation, while Leo goes to warn Camp Jupiter of an impending invasion and Apollo travels with Meg to search for the Erythaean Sybil.
As a sorceress, Calypso can command wind spirits to do her bidding. She loses most of her control of them when she gives up her immortality; however, she is still capable of summoning them to a degree, though by consuming more power than usual. Also, due to spending a long time at Ogygia, she has mastered sewing and lock-picking, which she uses while finding the gryphons at Indianapolis Zoo. She is Leo’s girlfriend as of “The Blood of Olympus”, “The Hidden Oracle”, “The Dark Prophecy”, and “The Burning Maze”.
Introduced in ''The Heroes of Olympus''
Leo Valdez
Leo Valdez is a son of Hephaestus. He likes to joke around and is very humorous. Though he does this mostly to keep himself happy and not too caught up in his tragic past, as well as so that his friends don't guess how broken he is inside. He is described as having curly brown hair, brown eyes, a cheerful face, a slim build, and a mischievous smile. He is Hispanic-American and speaks Spanish and machine. Leo has the ability to create and manipulate fire, a skill no child of Hephaestus has had for 400 years. He also has severe ADHD even by demigod standards. An excellent mechanic, he repairs a bronze dragon running wild in the camp's woods, naming it Festus. Inspired by a blueprint in Bunker 9, an abandoned bunker in the camp's woods, and a picture he drew in his kindergarten time, he also creates the Argo II, the ship the 7 of the Great Prophecy sail on to reach Greece.When Leo was eight, Gaia tricked him into burning down his mother Esperanza's machine shop in Houston resulting in her death. Leo's remaining family blamed him for killing her and left him a foster child and runaway. He meets Piper McLean at the Wilderness School in Nevada. Later, In The Lost Hero, he meets Jason Grace, who wakes up on a school bus headed to the Grand Canyon with no memories. However, Leo and Piper have Mist-induced memories of meeting and becoming friends with Jason. Leo uses his sarcasm and wit to hide his feelings, especially in regards of causing his mother's death. He sometimes thinks of himself as a seventh wheel, though he proves no less important or skilled than the others. In The Mark of Athena, Hazel learns her former boyfriend, Sammy Valdez, was Leo's great-grandfather. Until he falls in love with Calypso in The House of Hades, Leo flirts with almost every girl he meets in order to cover up his insecurities about never finding love. In The Blood of Olympus, Leo sacrifices himself to annihilate Gaia and dies in the process, but is brought back to life using the Physician's Cure and returns for Calypso on her island, Ogygia. This is an impressive feat, as nobody has ever found Ogygia twice. He and Calypso then journey back to Camp Half-Blood, sending a magic scroll ahead to let his friends know he's alive. When he does arrive at camp, everyone lines up to slap him for keeping them worried so long. As Leo is included in the prophecy of the Grove of Dodona, he and Calypso accept the task to accompany Apollo on his quests in The Dark Prophecy, at the end of which he announces that he and Calypso will be living at the Waystation and leading an ordinary life. When the prophecy of Trophonius requires that someone must warn Camp Jupiter from an invasion, Leo does the task alone.
Piper McLean
Piper McLean is a daughter of Aphrodite and the famous actor Tristan McLean. She is fifteen in The Lost Hero. Unlike most children of Aphrodite, Piper is not particularly concerned with beauty or fashion. Piper is Cherokee on her father's side. She has tan skin, eyes that change color constantly, and choppy caramel/chocolate-colored hair which she cuts herself. She is slim build and of average height. Her demigod "powers" include "charmspeak" and the ability to speak French. She is also occasionally able to see visions in her magic dagger Katoptris, which once belonged to Helen of Troy. The dagger lost that power after the battle against the giants in Athens.Piper's relationship with her father is mutually affectionate but strained, in part because of the small amount of attention he spares for her. When she was young, Piper used her persuasive skills to "borrow" things to earn a little of his time. After he is kidnapped by the giant Enceladus in The Lost Hero and subsequently rescued by Piper, Jason, and Leo, Mr McLean's relationship with his daughter begins to improve. Piper is also very close to Jason. Though she later learns it was all a trick of the Mist, she was once his girlfriend while they attended the same school. She works hard to recreate this relationship in real life when she comes to Camp Half-Blood. She is also friends with all of the seven quest members in The Heroes of Olympus, especially Annabeth and Leo.
Piper's main weapon is her dagger Katoptris, though she later acquires a magic cornucopia and uses it as a weapon. After being captured by pirates in The House of Hades, Piper asks Hazel to teach her sword fighting, using a jagged celestial bronze sword taken from one of the Boreads.
In The Hidden Oracle, Nico mentions that Piper is currently attending school in Los Angeles, together with Jason. In The Burning Maze, it's revealed that she broke up with Jason a few months earlier because their relationship was forced, and Piper did not like that. Apollo, as Lester Papadopoulos, was confused because the cloud nymph, Mellie, had seemed angry at Jason. This leads him to believe that Jason had broken up with Piper, but it was actually Piper who had. It is later unveiled that she wanted to discover herself and who she really was without the pressure of being the daughter of Aphrodite. The trick of the Mist that Hera used at the beginning of their relationship also contributed to the breakup as that meant that their relationship was technically "fake". Still, she is heartbroken when he dies by sacrificing himself to save her, Apollo, and Meg from Caligula.
Jason Grace
Jason Grace was a son of Jupiter and the mortal Beryl Grace, a TV star of the 1980s, and the younger brother of Thalia Grace. Jason has few memories of his mother, who was compelled to give him up when he was two, but he remembers enough about Thalia to not be surprised when he sees her again, in The Lost Hero. Thalia reveals that their mother told her that Jason was dead, and that this was what finally drove her to leave home, after she run away from home and found Camp Half-Blood. In The Blood of Olympus, that Beryl Grace had become a mania, or spirit of madness. He grew up at Camp Jupiter, the Roman equivalent of Camp Half-Blood, where demigods born to the Olympians' Roman aspects receive their training. In The Lost Hero, he begins a romantic relationship with Piper McLean.Jason is described as having blond hair, blue eyes, and a scar above his upper lip. He is of above-average height, with an athletic build and muscular arms. By the age of fifteen, he has earned the rank of praetor and leads the legion with his longtime partner, Reyna. Jason also coordinated the Roman camp's attack on the Titan force. He led an assault against Mount Tamalpais/Othrys, a Titan stronghold near San Francisco, and defeated the Titan Krios in combat, much as Percy Jackson defeated Hyperion and helped to defeat Kronos. Of all the characters in the series, Jason is the one who struggles the most with the differences between the Greek and Roman perspectives. Piper McLean describes Jason as very rule- and duty-oriented, though Terminus describes him as a "rule-flouter." When the Argo II is stuck in North Africa, he must choose one identity or the other. He chooses to consider himself a Greek, despite his parentage, and is later unable to command a legion of Roman ghosts. During The House of Hades it is revealed that Jason has plans to return to Camp Jupiter to improve it with things he learned at Camp Half-Blood, such as giving the fauns more rights and responsibilities. Later, during The Blood of Olympus, Jason decides to consider both the Greek and Roman traditions as part of his heritage. He becomes "Pontifex Maximus", a role which will see him travel between Camp Half-Blood and Camp Jupiter to build shrines for every god and goddess in the pantheon.
Although Jason and Percy immediately realize that it is best to work together, and become friends, their relationship is not without antagonism. As Percy puts it, it is natural for two powerful demigods to wonder which of them is stronger after a fight. Jason is a sword fighter like Percy, though they have different fighting styles. Jason uses an Imperial gold sword, styled as a Roman gladius, which he can extend into a pilum at will. Jason also has power over air currents and can fly. He can sense and control some air spirits and, like Thalia, call down lightning, which he conducts through his Imperial Gold weapons, and emit static shocks. Once, he and Percy together summon a hurricane in Charleston harbor. He is then killed during The Burning Maze, by Emperor Caligula. While other demigods, such as Frank, are rescued in later books, it seems that no such care was applied to Jason.
Hazel Levesque
Hazel Levesque is a thirteen-year-old demigod, a daughter of Pluto and Marie Levesque. She first appears in The Son of Neptune, at Camp Jupiter. It is later revealed that she has returned from the dead, assisted by her half-brother Nico. She grew up in the 1940s in New Orleans, where her mother had a gris-gris shop. When she was born, Pluto offered to grant her mother a wish, but her request for wealth backfired into an ability to control precious metals and gems, which both first view as a curse. Hazel died after Gaea tries to use Hazel's power over earth to resurrect Alcyoneus. When Hazel's mother changes her mind about helping Gaea, Hazel buries herself and her mother under the earth, delaying Alcyoneus's rebirth and killing them both. While Hazel's spirit is being judged, she gives up the chance to go to Elysium to save her mother from punishment, and they are both sent to the Fields of Asphodel instead. At some point before The Lost Hero, Nico finds Hazel in the Underworld while trying to visit Bianca di Angelo, only to find she has tried for rebirth. He helps her escape to the world of the living and arranges for her to join Camp Jupiter. Hazel and Nico are protective of each other, much as true half-siblings.Hazel is described as African American, having cocoa-colored skin, curly cinnamon-brown hair, and golden eyes. Her legion tattoo is described as looking like a cross with curved arms and a head. She is described as being very pretty, and is a strong female role model. She eventually learns to manipulate her curse, manipulating precious stones and metals and sensing structures underground. She is an accomplished horse-rider and skilled with a spatha. She tames the horse Arion, who eats precious metals. She is unusually knowledgeable about the Underworld because of her time there. During The House of Hades the goddess Hecate insists Hazel learn to manipulate the Mist. Hazel becomes very gifted at this. After the Second Gigantomachy, Hazel is promoted to the rank of centurion of the Fifth Cohort, succeeding her boyfriend Frank Zhang. Though she is much cooler than her boyfriend, she finds his inability to be cool endearing. Also as of The Trials of Apollo The Tyrant's Tomb Hazel is now a praetor of the twelfth legion with her boyfriend Frank Zhang.
Frank Zhang
Frank Zhang, nick-named "Chinese-Canadian baby man", by Hazel's horse, Arion, is a 16-year-old demigod, son of Mars and Emily Zhang, a Chinese-Canadian "legacy" who dies during military service in Afghanistan. He is taken care of by his grandmother after his mother's death, and makes his way to Camp Jupiter upon her insistence. Frank's family descends from Periclymenus, a grandson of Poseidon, who had the power to shapeshift. Periclymenus's descendants were sold into slavery in China, and migrated to Canada many years later. While battling Alcyoneus, Frank taps into his ancestral power and transforms into an elephant. However, his combined power of being a son of Mars and having the ability to shapeshift makes his life very fragile. The Fates tied his life force to a piece of firewood when he was a baby, so if the wood burns up, he will die. The goddess Juno appears to his mother and grandmother while he is a baby to warn them of this fact, as he would be crucial to defeating the Giants. In all his life, Frank has ignited the wood thrice, which he can do simply by thinking about it; the first time is while he is finding his way to Camp Jupiter, in bitter cold. The second time is when he, Percy, and Hazel travel to Alaska to free Thanatos. Eventually, Frank entrusts the firewood to Hazel, and in The House of Hades, Calypso creates a fireproof pouch to contain it.Frank has a meek disposition and is uncomfortable upon learning his father's identity publicly in front of the whole of Camp Jupiter. He suspected himself a son of Apollo, given his skill with a bow and arrow. On his quest in The Son of Neptune, and later during the series as well, he uses an enchanted spear given to him by Mars. To Frank's surprise, the spear summons a skeleton warrior that defeats the basilisks. Frank calls this skeleton "Gray".
As he has been residing in Camp Jupiter for no more than a year, Frank is initially considered a probatio, or rookie, of the Fifth Cohort. During the Roman War Games, Percy impresses everyone with his battle skills and instincts. Mars then shows up, and informs Frank he is his son, and that Frank is to lead a quest. Since only centurions are allowed to lead a quest, Reyna has to promote him to centurion rank. Later, in The House of Hades, Jason surrenders his praetorship to Frank, who uses its authority and Diocletian's Sceptre to lead an army of Roman skeleton soldiers against the monsters in the Necromanteion.
Frank was described as 'cuddly' and 'fuzzy' and with a chubby, babyish face in The Mark of Athena, but in The House of Hades, after summoning the blessing of Mars to defeat a hoard of enemies, he transforms. He is then described as being taller, more muscular, and without all his childhood fat. Though now built like a professional football player, he is still as sensitive as before, and is embarrassed at his new appearance at first.
Initially, he was wary of the tension between Hazel and Leo, as Leo reminded Hazel of her old boyfriend, Sammy Valdez. After Leo's encounter with Calypso, however, Leo became more relaxed around Hazel and there were no more signs of anything other than friendship, much to Frank's relief. He then pursues a relationship with Hazel.
Frank burns his stick for the final time in The Tyrant's Tomb to kill Caligula. Somehow the stick completely burnt, but Frank survived, freeing him from his curse.
Reyna Avila Ramírez-Arellano
Reyna Avila Ramírez-Arellano is a 16-year-old Puerto Rican demigod. She is a daughter of Bellona, a Roman Goddess of War, and the younger sister of Queen Hylla of the Amazons. She and her sister worked for Circe during the events of The Sea of Monsters. She is described as intimidating and a natural leader; she has glossy black hair and brown eyes so dark they look black. Reyna is generally more used to responsibility than other demigods, as she is a praetor at Camp Jupiter. Reyna's demigod "power" is the ability to lend her energy, skills, and character traits to nearby demigods. Similar to Leo Valdez, she can speak English Latin and Spanish. Reyna is often accompanied by two magical dogs, Aurum and Argentum, or by her pegasus Scipio. The immortal winged horse, Pegasus awards her the title of "Horse Friend", because of her kindness towards Scipio and others of his descendants.In The Blood of Olympus she, Nico, and Coach Hedge go on a quest to return the Athena Parthenos to Camp Half-Blood. While shadow-travelling to New York, the trio stops in San Juan and visits Reyna's former house, haunted by the ghosts of her relatives. There Reyna reveals that the Ramírez-Arellano family has always been favored by Bellona. Reyna's father deeply loved the goddess, but his PTSD turned this love into an unhealthy paranoia. When Reyna was ten years old, he became a mania, or an evil insane ghost. When the mania attacked Hylla, young Reyna picked up the closest weapon and killed what remained of her father. Reyna is reluctant to discuss the incident because patricide is "unforgivable" in New Rome. She formerly loved Jason Grace and Percy Jackson, but they rejected her.
Coach Gleeson Hedge
Gleeson Hedge is a satyr first mentioned in The Last Olympian, as the author of a distress call sent to Grover Underwood. Like Grover, Hedge is also a demigod Protector; his proudest "recruit" being Clarisse La Rue. He disguises himself as a coach at the Wilderness School to escort Piper McLean and Leo Valdez to Camp Half-Blood. He also serves as the adult chaperone for the Argo II and later accompanies the Athena Parthenos to camp. Despite his often warlike and often overly aggressive attitude, Hedge is kind and understanding to campers in need. He enjoys extreme sports and martial arts movies. In The Lost Hero, Hedge falls in love with Mellie the cloud nymph and marries her; by the time of The House of Hades, Mellie is pregnant with a satyr boy. Chuck, the baby, is born at the end of The Blood of Olympus, with Clarisse as his godmother. In The Hidden Oracle, Hedge, Mellie, Chuck, Piper, and Jason are spending the winter in Los Angeles.Introduced in ''The Trials of Apollo''
Apollo / Lester Papadopoulos
Apollo, in the mortal form of Lester Papadopoulos, serves as the main protagonist of The Trials of Apollo series.In The Heroes of Olympus, Apollo's Roman descendant Octavian promises the god many things for blessing his prophetic skills, which leads to the Olympians' distraction from the true threat of Gaia, and to the resurgence of Python. As a result, the Delphic Oracle ceases to function, effectively halting demigod quests, and Zeus punishes Apollo. Zeus's punishment consists of making Apollo mortal, though he retains most of his personality and some more minor powers. This punishment is revealed in The Trials of Apollo. In his mortal form, Apollo's name is Lester Papadopoulos.
Following a meeting with two thugs, Apollo encounters a demigod called Meg McCaffrey who claims him as her servant until he regains his godhood. There, Apollo has to adjust himself to a life of mortality and questing to regain his former powers and lifestyle. Apollo is released by Meg after the revelation of her alliance with his enemy.
As Lester, Apollo is a 16-year-old teenager with curly brown hair, blue eyes, acne, and a flabby torso. He is narcissistic, prideful, and arrogant, but does his best to not be a burden on others. His mortal transformation makes him realize how miserable humans are in facing the gods. In particular, he grows to deeply care for Meg and resolves to be with her despite the difficulties involved.
Meg McCaffrey
Margaret McCaffrey is a 12-year-demigod daughter of Demeter and the main character in The Hidden Oracle. Her father was murdered by "the Beast" and she was subsequently adopted by Emperor Nero, considering them as two separate people. Nero taught her the arts of a demigod and gave her a pair of crescent rings which can transform into sickles made of imperial gold, before giving her a task to lure Apollo into the Grove of Dodona. Meg appears to Apollo at an alley of Hell's Kitchen, Manhattan to defeat the thugs, also sent by Nero, to stage "robbery". Meg demands Apollo's servitude and with his travels to Camp Half-Blood with Percy's assistance. There, Meg displays unusual abilities even before Demeter claims her, and later goes with Apollo to search for missing demigods and the Grove in the nearby woods, having to endure a brief abduction in the process. Her relationship with Nero is revealed at the climax, but her growing doubtfulness regarding Nero's ways, not to mention her already familiar friendship with Apollo, leads her to rob Nero of his chance on burning the Grove. While she helps Apollo bring the Grove alive, she severs their bonding spell and leaves.In the second book, The Dark Prophecy, she returns to Apollo and helps him fight Commodus.
Meg is described as small and pudgy, with dark hair chopped in a messy pageboy style and black cat-eye glasses with rhinestones glittering and shimmering in the corners. She is Free-spirited and adventurous, inquisitive, and is also confrontational. She poses questions with no subtlety, something that Apollo is annoyed with but later comes to regard as a unique trait. Her abilities as Demeter's daughter allows her to connect better with nature as well as summoning a karpos called Peaches, a power that none of Demeter's other demigod children are known to possess.
Even though she is Demeter's daughter, not Ceres she fights like a Roman, with two swords; one for offense and one for defense. She is also known for her liking of unicorns in the fourth book The Tyrant's Tomb.
Hemithea
, known as "Emmie", is a retired Hunter of Artemis and caretaker of the Waystation. She lives with her partner, Josephine, also an ex-Hunter, and their daughter Georgia at the Waystation in Indianapolis. She and her sister were granted immortality by Apollo after escaping from the wrath of their father, King Staphylus. She then joined the Hunters of Artemis and fell in love with fellow hunter Josephine, so sometime in the 1980s, Josephine and Emmie gave up their immortality in order to grow old together. In The Dark Prophecy, she saves Calypso, Leo and Apollo from the Blemmyae with crossbow turrets and lets the trio stay at the Waystation. She comments on the similarities between Calypso and her half-sister Zoë Nightshade.Triumvirate Holdings
Triumvirate Holdings is a company that is led by three beings who are said to be the worst Roman Emperors in history. They force other people to worship them. During the Second Titanomachy, Triumvirate Holdings was responsible for giving Luke and his allies the Princess Andromeda, weapons, helicopters, and top human mercenaries. During the Second Gigantomachy, Triumvirate Holdings supplied Octavian with different weapons. Rachel described Triumvirate Holdings to be so rich that they make her father's company "look like a kid's lemonade stand." The trio have divided up North America into three major empires and are hunting for Oracles, which they plan to destroy.Among the known members of Triumvirate Holdings are:
- Emperor Nero – A legacy of Apollo and the main antagonist of The Hidden Oracle. The last in the Julio-Claudian dynasty, Nero is infamous for his tyranny and overindulgence in wealth and luxury with little regard to his subjects. He is the deified Roman Emperor, who has survived through the millennia along with two other deified Roman emperors—the Triumvirate. He forms an alliance with Python, who holds Delphi, while he himself controls the other oracles and plans to destroy Dodona. As the Emperor of the East, Nero lives in New York City, where he recruits and trains homeless demigods, and controls the eastern third of North America. He and the other two Roman Emperors have established Triumvirate Holdings. As "the Beast", Nero killed Meg's father, but later adopted and trained her in demigod arts so she could eventually lure Apollo into the Grove of Dodona. After Rhea restores the Grove of Dodona at Camp Half-Blood, Nero tries to force Apollo and Meg to burn the trees; failing at that, he sends a giant statue of himself, the Colossus Neronis, which originally stood in Rome, against Camp Half-Blood and Apollo and the Greek demigods defend the camp against it.
- Emperor Commodus - Commodus is the main antagonist of The Dark Prophecy and one of the three main antagonists in The Tyrant's Tomb alongside Caligula and Tarquin. The last in the Nerva-Antonine dynasty, Commodus ascended as emperor at a young age and was known for his good looks and musculature, for which he was nicknamed the "New Hercules". In later life, he became increasingly dictatorial and paranoid as he suspected that people would overthrow him. He also had preferences for gladiatorial battles and would buy slaves and exotic animals to fight to the death. Eventually, Apollo, with whom he had an affair, assassinated him while taking the form of Narcissus, his wrestling partner. As a god, he reigned as the Emperor of the Middle, ruling from a base at Indianapolis. He sends many of his men, including a kidnapped Georgie, to seek the Oracle of Trophonius, as he himself fears the oracle's reputed ability to drive its seekers insane. At the end of The Dark Prophecy, he launches an attack at the Waystation, but is defeated by Apollo and his group. Commodus manages to get away at the last second, having been blinded by Apollo's brief revelation of his true form. Later, Commodus joins forces with Caligula and Tarquin to destroy Camp Jupiter but ends up being killed by Apollo.
- Emperor Caligula - The main antagonist of The Burning Maze and one of the three main antagonists in The Tyrant's Tomb alongside Commodus and Tarquin. He was born into the first ruling family of the Roman Empire, conventionally known as the Julio-Claudian dynasty. Caligula was ambushed by his Germani guards which led to his mortal death. Following this incident, he employed the Strix and the Pandai to work for him while his fellow emperors continue to use Germani. Many years later, Apollo and Piper were brought to Caligula by his talking horse Incitatus as Caligula has the Pandai they subdued executed. Before he can have Meg and Jason Grace executed, Caligula is stunned when Apollo threatens to commit suicide. After Apollo stabs himself while Caligula kills Flange following the news of the attack on Camp Jupiter ending in failure, Caligula sails north with his guards. Medea meets with Caligula and advises that performs a ritual before Apollo dies. Caligula later fights Jason and Tempest on the back of Incitatus where he manages to kill Jason. After making sure that he is dead, Caligula sets sail for the Bay Area. Later, Caligula joins forces with Commodus and Tarquin to destroy Camp Jupiter but ends up being killed by Frank.
- King Tarquin - One of the three main antagonists in The Tyrant's Tomb alongside Commodus and Caligula. Tarquin is the last king of Rome and is depicted as a zombie. He participated in the Battle of San Francisco Bay where he targeted the Sibyillin Books. Tarquin was killed by Hazel and Diana.
Greek-Roman deities
Twelve Olympians
Though not all the gods who appear in Rick Riordan's novels are truly Olympians, all Greek and Roman gods are generally considered to be a subset of the Twelve Olympians. As such, most characters in the series refer to these immortals generally as the "Olympian gods", to distinguish them from the Greco-Roman [|primordial gods] and Titans.- Zeus/Jupiter – The king of the gods, Zeus is most prominent in The Lightning Thief but has several roles throughout the rest of Percy Jackson & the Olympians. Zeus is shown prominently throughout the series to be extremely narcissistic, paranoid and hypocritical. In The Lost Hero, under the influence of Khione, Zeus forbids contact between gods and mortals and closes off Olympus, although he indirectly helps the protagonists several times on their quests. As the primary Olympian god, his demigod children reside in Camp Half-Blood's biggest cabin, Cabin 1, although there is only one person who resides there at the end of The Heroes of Olympus: Jason. In the film adaptation, Zeus is played by Sean Bean.
- Hera/Juno – The queen of the gods who plays a role in The Titan's Curse, by helping Percy and the others on their quest in The Battle of the Labyrinth. As Juno in The Lost Hero, she is kidnapped by Gaea, and contacts Jason Grace to rescue her. Previously, as Juno, she had sneaked out of Olympus and switched Percy and Jason to try to unite the Roman and Greek demigods, going against the wishes of Zeus as part of a plan to defeat Gaea. Her cabin in Camp Half-Blood is Cabin 2, the second biggest in the camp, but because she does not have demigod children, it is empty. In the film adaptation, Hera is played by Erica Cerra.
- Poseidon/Neptune – The god of the sea, earthquakes, and horses who is the brother of Zeus and Hades. In The Lightning Thief, he is suspected of having stolen Zeus's master bolt but is proven innocent after Percy recovers it from Ares. Poseidon fights Oceanus in the underwater front of the Titan war. He remains there in The Last Olympian while the other Olympians fight Typhon, until Percy convinces him that his power is necessary to defeat Typhon. He was last seen fighting the Giants in the Second Gigantomachy alongside Percy and the other gods and demigods and mentioned Kymopoleia to the other gods as his daughter after Percy and Jason reported meeting her. Though he is referred to as Neptune in the sequels of Percy Jackson and the Olympians when the Greeks and Romans are united, he has yet to appear in Roman form. His cabin in Camp Half-Blood is Cabin 3 in which Percy is the sole permanent occupant. In the film adaptation of The Lightning Thief, Poseidon is played by Kevin McKidd. In the musical, he is portrayed by Jonathan Raviv.
- * Amphitrite/Salacia – The wife of Poseidon/Neptune. She appears in one scene of The Last Olympian and is described as a beautiful goddess wearing armor, with black hair and small horns like crab claws.
- * Delphin/Delphinus – The god of dolphins, and one of Poseidon's lieutenants. He was seen briefly during a war council meeting in Poseidon's palace in The Last Olympian, in the shape of a dolphin.
- * Palaemon – The god of sharks, and one of Poseidon's lieutenants in the war against Oceanus.
- * Triton – A sea god depicted as a merman with two fishtails. He acts arrogant toward Percy but respects Tyson.
- Demeter/Ceres – The goddess of agriculture, who appears alongside her daughter Persephone in The Last Olympian, where they participate in the battle against the Titans. Demeter's cabin in Camp Half-Blood is Cabin 4. In the film adaptation of The Lightning Thief, Demeter is played by Stefanie von Pfetten.
- Persephone/Proserpine – The goddess of spring, and the queen of the underworld. Persephone is the wife of Hades and the daughter of Demeter and Zeus. Hades only allows her to visit Demeter, her mother, in the spring and summer. She is said to be able to "soften" Hades and make him more merciful. Unlike most minor gods, she sides with Olympus during the war against the Titans. In the film adaptation, Persephone is played by Rosario Dawson.
- Ares/Mars – The god of war who is the son of Zeus and Hera and the father of Deimos, Phobos, Eros, Clarisse La Rue, and Frank Zhang. Ares is a callous bully who is driven by either greed, aggression, violence or by the promise of violence. However, as Mars, he dislikes war without reason and is one of the more important Roman Gods. He is however still a bully and is all for killing the Greeks. Percy first encounters Ares in The Lightning Thief, in which he drives a black Harley-Davidson motorcycle with flame decals and a leather seat made from human skin. Percy defeats Ares in a sword fight near the climax of the book. Cabin 5 in Camp Half-Blood is the home of Ares' demigod children; it is said to be surrounded by all kinds of warfare apparatus, including spikes. In the film adaptation of The Lightning Thief, Ares is played by Ray Winstone. In the musical, he is played by James Hayden Rodriguez.
- * Deimos – The god of terror. A son of Ares, Deimos only appears in the short story "Percy Jackson and the Stolen Chariot" in The Demigod Files, where he torments Clarisse, forcing Percy and Clarisse to cooperate to defeat him.
- * Phobos – The god of fear. A son of Ares, Phobos only appears in the "Percy Jackson and the Stolen Chariot" story in The Demigod Diaries, where he torments Clarisse along with his brother. He has the power to show people their greatest fears, but Percy and Clarisse cooperate to defeat him. In The Blood of Olympus, a statue of Phobos is used by Piper to kill Mimas which fulfills the requirement of "one god and one demigod cooperating" in killing giants.
- Athena/Minerva – The goddess of wisdom, and the daughter of Zeus and Metis. Athena first appears in The Titan's Curse, where she dislikes Percy and his relationship with her daughter, and votes to execute Percy due to his crucial role in the fate of Olympus. She then argues that it was the most logical and wise choice. As Minerva, she is a scatterbrain and lost. She hates the Romans for reducing her to that and tells her descendants to kill the Romans. She also leads her best children to the Athena Parthenos, although Aphrodite believes it to be subconscious, as Athena doesn't know where it is. Her color scheme is grey, and her cabin in Camp Half-Blood is Cabin 6. In the film adaptation, Athena is played by Melina Kanakaredes.
- Apollo – The god of the sun, light, music, truth, and healing. He serves as a supporting character in Percy Jackson & The Olympians and The Heroes of Olympus series, and becomes the main protagonist of The Trials of Apollo series as a mortal named Lester Papadopoulos. Apollo first appears in The Titan's Curse, where he transports a group of demigods and Hunters at the behest of his twin sister Artemis. Later, he assists the quest group in rescuing Artemis from the Titans, even though doing so has been forbidden by Zeus. At the end of The Last Olympian, Apollo chooses Rachel Dare as his new Pythia. After the war in the second series, the furious Zeus punishes Apollo with mortality for his failure to identify Gaea as a threat. In the of The Lightning Thief, Apollo is played by Dimitri Lekkos.
- Artemis/Diana – The goddess of the moon, animals, youth, and hunting. Artemis is the daughter of Zeus and Leto and the twin sister of Apollo. Artemis, true to her vows, is distrusting of men who discourages the companionship or value of men, and encourages maidenhood. As a result, she has no demigod children, but recruits Hunters who serve as her companions and attendants. Cabin 8 is her honorary home at Camp Half-Blood, but because she is a virgin, it is populated only when her Hunters come to visit. In the film adaptation of The Lightning Thief, Artemis is played by Ona Grauer.
- Hephaestus/Vulcan – The gods' blacksmith, and the father of Charles Beckendorf and Leo Valdez. At Camp Half-Blood, Cabin 9 is dedicated to him. Hephaestus acts as a major ally of Percy in The Battle of the Labyrinth. In The Lost Hero, he defies Zeus by speaking to Leo through his dreams and delivers the head of the mechanical dragon Festus for use as the figurehead for the Argo II. In the film adaptation of The Lightning Thief, Hephaestus is played by Conrad Coates.
- Aphrodite/Venus – The goddess of love and beauty, who first appears briefly in The Titan's Curse. Her appearance shifts constantly, always becoming more beautiful. Cabin 10 at Camp Half-Blood is the home of her demigod children. In The Lightning Thief, Aphrodite is played by Serinda Swan.
- * Eros/Cupid – The god of love who is the son of Aphrodite/Venus and Ares/Mars. In The House of Hades, Jason and Nico convince Cupid to give them Diocletian's Scepter.
- Hermes/Mercury – The messenger of the gods, and the god of travelers and thieves. He is the son of Zeus and Maia. In the Percy Jackson and the Olympians series, Hermes helps Percy, hoping that he will be able to redeem Luke. All unclaimed demigods are packed into Hermes' cabin, Cabin 11 because Hermes welcomes all travelers. In the film adaptations, Hermes is played by Dylan Neal in the first film and by Nathan Fillion in the second.
- Dionysus/Bacchus – The god of wine, parties and madness who is the son of Zeus and Semele. Dionysus was made the head of Camp Half-Blood as punishment for pursuing "an off-limits wood nymph" romantically. Dionysus is portrayed as a cynical and unfriendly misanthrope who does not appear to have much respect for other beings, except for Ariadne. He is a powerful god, but his powers are shown the least throughout the series. He has two demigod sons named Castor and Pollux, both of whom are the sole inhabitants of Cabin 12. Dionysus hates his job and has a low opinion of demigods, likening them to Theseus and his abandonment of Ariadne. Dionysus is played by Luke Camilleri in the first film and by Stanley Tucci in the second. In the musical, he is portrayed by George Salazar.
- Hades/Pluto – The god of the Underworld, and brother of Zeus and Poseidon. He is an isolationist who distances himself constantly from other gods because they do the same to him, primarily out of fear. They continuously underestimate Hades who is in fact a very honorable and fatherly individual. He is the father of Nico di Angelo, Bianca di Angelo, and Hazel Levesque. After the Second Titanomachy, Hades is granted Cabin 13, which is populated by his demigod child Nico. In the film adaptation of The Lightning Thief, Hades is played by Steve Coogan and is depicted as having a fiery winged demon form.
- Hestia/Vesta – The goddess of the hearth and home. Like Artemis, she swore a vow of chastity so no conflict can spring up about her allegiance; as a result, she does not have any demigod child. Hestia gives up her golden throne on Olympus to Dionysus/Bacchus to keep the peace on the Olympian counsel, making the number of male and female gods unbalanced with seven men and five women. She is the title character of The Last Olympian, where she helps Percy figure out how to defeat Kronos. She is described as preferring the shape of a young and softspoken girl with brown hair.
Minor Greco-Roman gods
- Achelous – A river god with the face of a man and the head of a bull. He had previously fought with Hercules where Hercules removed one of Achelous' horns; his other horn plays a part in the plot of The Mark of Athena in which it is removed by Piper McLean and becomes a cornucopia.
- Aeolus – The god of the winds. In The Last Olympian, he manipulates the winds to form a barrier around Olympus that protects it from air attacks from the Titans. In The Lost Hero, he is portrayed as frenetic and unbalanced by attempting to fill all the requests of the gods and hopes to be made god of the wind.
- Anemoi – The four Wind Gods.
- * Boreas/Aquilon – The god of the north wind and winter. He is first seen in The Lost Hero where Jason, Piper, and Leo ask for assistance. He has two immortal children called the Boreads and is the father of Khione.
- * Khione – The goddess of snow, who is the daughter of Boreas and sister of the Boreads. She first appears in The Lost Hero when she betrays Jason, Piper, and Leo to the forces of Gaea.
- * The Boreads – The sons of Boreas and the brothers of Khione. Calais is depicted as a big simpleton who struggles with words that have more than two syllables, while Zethes is shown to be heterosexual and to maintain an eighties hairstyle. In The Lost Hero, the Boreads are seen with Boreas. In The House of Hades, Khione and the Boreads attack the Argo II. The three of them are defeated when Piper McLean charmspeaks Festus to life. Piper also takes one of the Boreads' celestial bronze sword.
- ** Notus/Auster – The god of the south wind and summer. He appears in The House of Hades.
- ** Zephyrus/Favonius – The god of the west wind and spring. He appears in The House of Hades.
- ** Eurus/Vulturnus - The god of the east wind and autumn.
- Asclepius/Vejovis – The god of healing who is the son of Apollo and Phoebus. In The Blood of Olympus, Asclepius is first mentioned by Apollo on Delos, as the only person to have ever successfully cured death. Apollo gives Leo, Frank, and Hazel his location in Epidaurus. Piper, Leo, and Jason later meet Asclepius in the Asclepion. He quickly diagnoses Jason with myopia and gives him a pair of glasses. Later, he uses the Pylosian mint and the Makhai to formulate the physician's cure and gives the trio instructions on its use.
- Enyo/Bellona – The goddess of war, who is the mother of Hylla and Reyna. Though she is never seen in the series, she indirectly helps Reyna to kill Orion by empowering her with her strength.
- Britomartis - The goddess of hunting and fishing nets. In The Dark Prophecy, she encounters Apollo, Leo Valdez, and Calypso at the Waystation where she tasks them to retrieve her pet gryphons, Heloise and Abelard, as payment for the secret route to the lair of Commodus. Later, she contacts the Hunters of Artemis to serve as backup for the protection of Waystation.
- East River – A river god who personifies the river in New York. The East River only appears in The Last Olympian, where he sinks Titan ships coming to attack Olympus for half a sand dollar given to him by Percy.
- Elpis/Spes – The goddess of hope. She remains in Pandora's pithos as the only thing for humans to keep when other evils were released to the world. In The Last Olympian, the pithos is given by Percy to Hestia by the reasoning that hope remains the safest in hearth. In The Blood of Olympus, Gaea times her awakening to coincide with the Feast of Spes, a Roman festival honoring the goddess.
- Eris/Discordia – The goddess of chaos and the daughter of Nyx. In The House of Hades, Percy and Annabeth encounter Eris alongside Nyx and Eris' siblings near the Mansion of Night.
- Ganymede – The cupbearer of the gods, who appears in The Sea of Monsters as part of a public service announcement advising users of the Gray Sisters' taxi service to use the seat belt. In Percy Jackson: Sea of Monsters, Ganymede is played by Richard Yearwood.
- Geras – The goddess of old age and the daughter of Nyx. In The House of Hades, Geras is among the children of Nyx that encounter Percy and Annabeth near the Mansion of Night.
- Harpocrates - The god of silence, who was imprisoned by Triumvirate Holdings and used to silence all demigod communications.
- Hebe/Juventas – The goddess of youth, who is the daughter of Zeus and Hera and wife of Heracles. Hebe is among the minor gods who allied themselves with the Titans; after the war, she is awarded Cabin 18 in Camp Half-Blood.
- Hecate – The goddess of magic, who is an ally of Kronos in the Percy Jackson and the Olympians series, but does support the gods against Gaea. Her empousai minions and her daughter Circe is a feminist that morphs men into pigs and torments Percy in The Battle of the Labyrinth and The Sea of Monsters, respectively. After the Titans are defeated, she reconciles with Olympus and is granted Cabin 20 at Camp Half-Blood for her children. In The House of Hades, she helps Hazel defeat the giant Clytius in front of the Doors of Death in Epirus.
- Hudson River – A river god who personifies the river in New York. He only appears in The Last Olympian, where he sinks Titan ships coming to attack Olympus for half a sand dollar given to him by Percy.
- Hypnos/Somnus – The god of sleep, son of Erebus and Nyx and father of Morpheus and Clovis, the latter of whom is his demigod child in Camp Half-Blood. He has Cabin 15 at Camp Half-Blood.
- Iris/Arcus – The goddess of rainbows, who administers a network of rainbows used by demigods and Olympians to communicate remotely. She is the mother of the demigod Butch, who makes a small appearance in The Lost Hero, who was the company of Annabeth in finding "the boy with one shoe" which was Jason Grace. After the Second Titanomachy, she is granted Cabin 14 for her demigod children. In The Son of Neptune, she meets Frank, Percy, and Hazel on their quest in finding the missing legion's eagle.
- Janus – The god of gates, doorways, beginnings, and endings; he appears as a minor character in The Battle of the Labyrinth. He has two faces, and each face seems to think the exact opposite of what the other face thinks.
- Kymopoleia – The goddess of sea storms and a daughter of Poseidon. She is bethrothed to Briares the Hekatonkheire, whom she resents. In The Blood of Olympus, Kymopoleia works with Polybotes to hinder the demigods while sailing through the Aegean Sea after feeling abandoned by her father. She is convinced by Jason to switch sides, because she wants to be feared and respected. Together, they kill Polybotes. She is nicknamed "Kym" by Percy.
- Lares – Household gods and ancestor spirits who are guardians at Camp Jupiter.
- * Cato – A Lare. In The Son of Neptune, Cato is seen at the senate meeting where Frank Zhang is made a Centurion.
- * Vitellius – A Lar who is a descendant of Asclepius. In The Son of Neptune, he was first seen when Hazel was introducing Percy to him.
- Morpheus/Somnia – The god of dreams and son of Hypnos. He is among the minor gods that appears as an ally of Kronos in The Last Olympian. He puts the entire city of New York to sleep during the battle.
- Melinoë – The goddess of ghosts, who lives in the underworld. She appears only in The Demigod Files in the short story "Percy Jackson and the Sword of Hades", where she scares people by showing them the ghosts of deaths they regret.
- Mithras - The Roman god of warriors, who is mentioned by Aphrodite in The Mark of Athena when she talks about how Athena was changed by the Romans. Later Annabeth stumbles on a cult of ghosts dedicated to him, who look down on her for being a girl. She realizes everything they are talking about from pictures, statues and the corpses of other dead children of Athena in the cult's chamber, and manages to escape.
- Nike/Victoria – The goddess of victory; Leo Valdez, Hazel Levesque, Frank Zhang, and Percy Jackson meet her in The Blood of Olympus and later kidnap her. She is also on the Athena Parthenos in Athena's hand. Her children are in Cabin 17 at Camp Half-Blood.
- Nemesis – The goddess of vengeance and mother of the late Ethan Nakamura. After the Second Titanomachy, she is granted Cabin 16 for her demigod children. Nemesis is seen in The Mark of Athena where she gives Leo a cursed fortune cookie.
- Pan/Faunus – The late god of the wild and patron of all satyrs. Pan has been missing for over 2000 years and the satyrs seek him fervently. After Percy and his friends find Pan in The Battle of the Labyrinth, he dies peacefully and releases his spirit to Percy, Grover, Rachel, and Annabeth. In The Last Olympian, Grover carries on the legacy of Pan by sending teams of satyrs to clean up the world.
- Pomona – The Roman goddess of plenty. Pomona isn't seen in person, but a statue of her speaks in The Last Olympian, becoming irritated when she is mistaken for Demeter by Percy, throwing bronze apples at Percy and Will Solace.
- Terminus – The Roman god of boundaries. In The Son of Neptune, Terminus is portrayed as obsessive-compulsive and obsessed with order. He guards the city limits of New Rome. Terminus also helps Percy defeat the giant Polybotes.
- Thanatos/Letus – The god of death, and a lieutenant of Hades. In The Son of Neptune, the forces of Gaea capture Thanatos, allowing their dead allies to quickly return to life. He resumes his duties after being rescued by Percy, Hazel, and Frank.
- Tiberinus – A river god who appears to Annabeth in The Mark of Athena. He guides her to the beginning of the Roman leg of her quest for the Athena Parthenos. To Annabeth, he looks exactly like Gregory Peck.
- * Rhea Silvia – Rhea Silvia is a former Vestal Virgin who mothered Romulus and Remus, the founders of Rome. She was made an immortal and wife of Tiberinus after she was given a death sentence for breaking her chastity vow. In The Mark of Athena, Rhea Silvia and Tiberinus give advice to Annabeth about the location of the Athena Parthenos. She is described as looking like Audrey Hepburn.
- Triptolemus – The god of farming who is associated with Demeter. In The House of Hades, he cures Hazel and Nico from the poison of the Katoblepones after Frank obtained a serpent to repair his chariot.
- Tyche/Fortuna – The goddess of fortune, who was awarded Cabin 19 at Camp Half-Blood after the Second Titan War. Her Roman counterpart Fortuna is celebrated by Camp Jupiter in the "Feast of Fortuna" on 24 June every year to decide what fortune that would befall the camp.
Primordial deities
- Gaia/Terra – The embodiment of Earth who and the primary antagonist of The Heroes of Olympus series. Gaia is the wife of Ouranos, and mother of the Titans, the Elder Cyclopes, the Hekatonkheires, the Giants, and Antaeus. She is the grandmother of the Olympians, whose rule she resents. As of The Son of Neptune, she remains sleeping in the ground, but retains some consciousness and influence. Like Kronos, she commands an army of mythological figures and monsters dissatisfied with the Olympians. During The Blood of Olympus, she is defeated by Leo Valdez, Piper McLean and Jason Grace who lift her into the sky, charm her to sleep and then incinerate her with a mighty blast of fire combined with a shot from an onager by Octavian, a legacy of Apollo and the former augur of Camp Jupiter. As a goddess she can't be killed, but like her son Kronos, her essence is scattered so much she will never able to form a consciousness again.
- * Ourea – The primordial gods of the mountains and the children of Gaea. In The House of Hades, there were some Ourae that make up the Apennine Mountains. When the Argo II tries to cross the Apennine Mountains, the Ourae there attack them with boulders because they are loyal to Gaea. They hurl boulders from their mountaintops where they severely damage the Argo II. Leo Valdez has to turn the Argo II away from the Apennine Mountains in order to come up with a different plan.
- Akhlys – The goddess of misery, and a daughter of Chaos and Night. She is described as a miserable-looking old woman who carries the Aegis shield with Medusa's head carved into it. In The House of Hades, she offers the Death Mist to Percy and Annabeth, but later betrays them by luring them into Nyx's territory and trying to kill them with poison. In anger, Percy manipulates the poison back at Akhlys, causing her to run away in fear. This is the first time that Annabeth sees the darker part of Percy's personality.
- Keto – A primordial sea goddess and the sister and wife of Phorcys. In The Mark of Athena, Keto appears as a girl named "Kate" who is encountered in Phorcys' aquarium in Atlanta. When Gleeson Hedge discovers Phorcys' ruse, he frees Percy and Frank after knocking "Kate" out. After Percy, Gleeson, and Frank escape from the aquarium, Keto sends a skolopendra after them.
- Nyx – The primordial goddess of night, said to be the oldest being in the universe besides Chaos itself. In The House of Hades, Percy and Annabeth accidentally wander into Nyx's territory and try to pose as tourists guided by a brochure that does not mention Nyx. Angered, Nyx shows just how important she is and summons her children, who emit pitch-black darkness that even Nyx herself cannot see through it. Before she can catch them, the couple leave through the Mansion of Night. Nyx is described by Annabeth to be "as tall as the Athena Parthenos, but very much alive."
- Ouranos – The embodiment of the sky, who is the husband of Gaea and the father of the Titans. When Gaea gave birth to the Elder Cyclopes and the Hekatonkheires, Ouranos hurled them into the pits of Tartarus because of their ugly appearances. Kronos later castrated Ouranos before cutting him to pieces. Ouranos then cursed Kronos, stating that his child would come to overthrow him just as he had. Not much is mentioned about Ouranos afterwards. In Percy Jackson's Greek Gods, Percy Jackson describes Ouranos to be tall and muscular with long dark hair and his skin changing depending on if it is day or night.
- Phorcys – A primordial sea god and the brother and husband of Keto. In The Mark of Athena, he and Keto run an aquarium in Atlanta, Georgia which contains many rare sea monsters. Following a "VIP" tour, Phorcys traps Percy and Frank in a tank to fight each other. This attracts the attention of Gleeson Hedge, who manages to break the glass tank as they escape promising to return and free the sea creatures that Phorcys has in captivity.
- Styx – The primordial river goddess of the same name. Taking oaths under Styx' name binds people into a contract; breaching them will mean consequences, oftentimes misery, for them. While multiple people have sworn under Styx' name, Styx herself does not appear until The Dark Prophecy, where she appears in Apollo's vision threatening him with punishment for breaking his oath of not playing music or practicing archery until he regains his immortality.
- Tartarus – While Tartarus is the name of a location where the Titans were imprisoned, there is a primordial god by that name as well. Through Gaea, Tartarus fathered Typhon and the Giants. His real form is the whole Tartarus itself, but he personifies himself in a form that stands several feet tall with a face of a swirling vortex and a voice that makes it seem going inward, rather than outward. In The House of Hades, the personification of Tartarus appears in physical form where he makes a remark about Gaea's awakening. Annabeth and Percy fight Tartarus until Iapetus and Damasen sacrifice themselves so that Percy and Annabeth can get out of Tartarus.
Titans
- Kronos/Saturn – The king of the Titans, the Lord of Time, and the main antagonist of the Percy Jackson and the Olympians series. He is the father of all the elder Olympians, as well as Chiron. He fights with a scythe with a six-foot-long magical blade that can harm both gods and mortals and was used to dismember his father Ouranos. Kronos is initially trapped in Tartarus, but eventually escapes to possess Luke Castellan. In this form, he personally leads the Titan army against Olympus. He is finally defeated by his own host, in fulfillment of the first Great Prophecy. In Percy Jackson: Sea of Monsters, Kronos is voiced by Robert Knepper. He was shown to have a gigantic, demonic body along with superhuman strength and the ability to use parts of his own body as projectile weapons.
- Rhea – The queen of the Titans, and the mother of the elder Olympians. Unlike Kronos, Rhea loved the children that she gave birth to and even kept Zeus from being eaten. Since Kronos' defeat, Rhea retreats to Upstate New York, but continues to keep in touch with her children. In The Hidden Oracle, Apollo learns that an oracle that Rhea created called the Grove of Dodona is the only one yet to be conquered by Nero. Rhea subsequently appears to Apollo to offer him advice.
- Aigaios – A partner of Oceanus who assists in the Titans' War against Poseidon. In The Titan's Curse, Tyson reports that Aigaios protected the Princess Andromeda from Poseidon's wrath.
- Atlas – The general of the Titan army. He is the father of Calypso and the five Hesperides, one of them being Zoë Nightshade, who is later disowned because she helped Hercules steal the golden apples. Atlas was imprisoned on the mountaintop of Mount Tamalpais near San Francisco, forever cursed to hold up the sky. He is extremely powerful and strong, even for a Titan. He served as the primary antagonist in The Titan's Curse, but is mocked by the other Titans in later books for his failure. He does not participate in Kronos's final assault.
- Helios - The Titan of the Sun and the grandfather of Medea. In The Titan's Curse, Apollo mentions that Helios and Selene faded when the Romans took over and his role was given to him. In The Burning Maze, Medea summons her grandfather from the depths of Tartarus so that she can absorb his power alongside the essence of Apollo and make Caligula the new God of the Sun. Helios is summoned again to fight Apollo, Piper, and Meg. When Medea is defeated, Helios goes supernova. When Apollo encounters Helios in the burning maze, Apollo promises to free him from Medea's control in exchange that he lets them pass. After Piper kills Medea and frees Helios from his prison, Apollo persuades Helios to hold his rage and finally rest while planning to keep his memories alive.
- Hyperion – Titan of the East. Hyperion is the father of Helios and Selene, the Titans of the sun and moon, respectively. He appears in The Last Olympian, where he is clad in full golden armor and battles Percy. He has all the powers of the Sun. Grover Underwood traps Hyperion by turning him into a tree. In The House of Hades, Hyperion is stopped from reforming in Tartarus by his brother Iapetus. He and Krios are seen later guarding the Doors of Death. Both are obliterated by the physical form of Tartarus as a show of power.
- Iapetus/Bob the Titan – Lord of the West. First seen in The Demigod Files story "Percy Jackson and the Sword of Hades," when Percy drags him into the River Lethe, erasing his memory. Rather than kill him, Percy renames him "Bob" and sends him to work for Hades. In The House of Hades, he helps Percy and Annabeth escape Tartarus because of Nico di Angelo's kind description of Percy. Annabeth is afraid that he will regain his memories by meeting with his fellow Titans, but Iapetus continues to help them and later sacrifices himself to fend off Tartarus while they use the Doors of Death. In the outside world, Percy fulfills Iapetus' final wish by looking at the stars and saying "hello" for the Titan. Bob befriends a small sabre cat while in Tartarus, as well as the giant Damasen.
- Koios – Lord of the North. In The House of Hades, Koios is briefly seen in Tartarus. He mentions that his daughter Leto had been mistreated by Zeus after "she bore him those fine twins". Percy describes Koios as having Apollo's smile and Artemis's eyes.
- Krios – The Titan of Stars and constellations and Lord of the South. Percy first sees Krios in a dream during The Last Olympian. He wears armor decorated with glowing stars. In The Lost Hero, Jason claims to have defeated Krios in single combat on Mount Othrys at the same time of the events happening in The Last Olympian. In The House of Hades Krios is seen with Hyperion guarding the Doors of Death. Both of are obliterated by Tartarus's physical form.
- Leto - The mother of Apollo and Artemis. In The Dark Prophecy, Lester has a vision of Leto begging Zeus to lift Apollo's punishment and allow him to return to Mount Olympus. Zeus refuses stating that Apollo's real test is yet to come.
- Oceanus – The Titan of the Ocean. Oceanus is depicted as having the upper body of a muscular man with a long beard and horns and the lower body of a serpent. He did not fight the Olympians in the original Titanomachy, but in The Last Olympian, he assaults Poseidon's forces underwater. Oceanus is incredibly powerful and his intense battle with Poseidon lasts for days and creates storms and tsunamis. After the defeat of Kronos, Oceanus escapes back to the depths of the ocean.
- Prometheus – The Titan of Forethought. Like Oceanus, Prometheus prefers to fight for the more powerful side. He supported the Olympians in the first Titanomachy but joins with Kronos in the second, in part because of Zeus's cruel punishment for Prometheus's gift of fire to mankind. This punishment ended only with the hero Hercules, a fact Prometheus uses to justify his claims to love heroes. He is sent to negotiate Percy and Thalia's surrender during the Battle of Manhattan, offering them the spirit of Elpis. He flees after Kronos's defeat, sending a list of excuses to Mount Olympus.
Gigantes
- Alcyoneus – A 40 ft. Gigantes with rust-colored dragon-like legs whom Hazel Levesque almost resurrects during World War II. Alcyoneus eventually rises in The Son of Neptune. He is invincible as long as he remains in his homeland which after his resurrection is Alaska. Frank, Hazel, and Arion defeat him after driving him into Canada. He opposes Hades/Pluto.
- Clytius – A 20 ft. Gigantes with ash-colored dragon-like legs. He opposes Hecate. Clytius appears in The House of Hades. He guards the living side of the Doors of Death in Epirus. He is defeated by Hecate, Jason, Leo, Piper, Nico, Frank and Hazel.
- Damasen – A 20 ft. peaceful Gigantes with red dragon-like legs who appears in The House of Hades and is exclusive to the series. He had been made to oppose Ares/Mars. Damasen had been exiled to Tartarus as he was peaceful not violent and for refusing to take part in the ancient fight against the gods and Hercules. Percy and Annabeth encounter him in Tartarus when Iapetus brings them to his lair. When the personification of Tartarus arrives near the Doors of Death, Damasen confronts him with Iapetus so that Percy and Annabeth can escape back to the living world.
- Enceladus – A 30 ft. Gigantes with green dragon-like legs. Enceladus was the first Giant to be reawakened in the Heroes of Olympus series. He opposes Athena/Minerva. In The Lost Hero, Enceladus is killed by Jupiter and Jason as the Giants can only be killed by a god and a hero working together. In The House of Hades, Enceladus re-enters the world through the Doors of Death.
- Ephialtes and Otis – Ephialtes and Otis are twin 12 ft. Gigantes that look somewhat more human than most of their brothers since they each have two snakes for legs. They both oppose Dionysus/Bacchus. Ephialtes and Otis are awakened in The Mark of Athena by Gaea. Ephialtes and Otis manage to capture Nico di Angelo and were tasked by Gaea to kill all demigods of prophecy but two, whom they are to bring to her. They fight Jason and Percy who defeat them with the help of Bacchus. In The House of Hades, Ephialtes and Otis they return to the living world through the Doors of Death.
- Hippolytos – The 30 ft. Messenger of the Gigantes with orange dragon-like legs. He opposes Hermes/Mercury. Hippolytos makes a minor appearance in The Blood of Olympus.
- Mimas – The 25 ft. Gigantes with charcoal-colored dragon-like legs. He opposes Hephaestus/Vulcan. Mimas makes a minor appearance in The Blood of Olympus.
- Orion – A 20 ft. Gigantes who opposes Apollo and Artemis/Diana and is exclusive to this franchise. In The Heroes of Olympus, Orion is sent by Gaea to hunt down Nico di Angelo, Reyna Avila Ramírez-Arellano, and Gleeson Hedge throughout their journey of bringing the Athena Parthenos from Greece to New York in attempt to stop the two camps from destroying each other. He nearly catches them numerous times, but they either shadow travel away before he has the chance or are saved by allies. Orion murders countless Hunters and Amazons, including Phoebe, but escapes with his life. Much later, Reyna impales him through the heart with her dagger.
- Periboia – The female Princess of the Gigantes who is Porphyrion's daughter. She opposes Aphrodite/Venus. Periboia appears in The Blood of Olympus.
- Polybotes – A 30 ft. Gigantes with Komodo dragon-like legs. He opposes Poseidon/Neptune and can turn water to poison. Polybotes attempts to destroy Camp Jupiter in The Son of Neptune with an army of monsters. He is killed by Percy and Terminus. He expresses a particular desire to capture Percy and make him watch as he kills Poseidon. In The House of Hades, Polybotes returns to the living world through the Doors of Death and later convincing the goddess Kymopoleia in joining the giants but was again defeated by Jason Grace and the goddess Kymopoleia herself after Jason convinced her to turn sides.
- Porphyrion – The 40 ft. King of the Gigantes with green dragon-like legs that are described to be the same color as lima beans. He opposes Zeus/Jupiter. Awakened in The Lost Hero, Porphyrion fights Jason and his friends. Hera almost kills him, but he escapes.
- Thoon – A shriveled wizened Gigantes with white dragon-like legs. He opposes the Fates. Thoon makes an appearance in The Blood of Olympus.
Demigods
- Alabaster Torrington – Alabaster appears in the short story "Son of Magic" in The Demigod Diaries. He is the son of Hecate and half-brother of the murderous monster Lamia. Alabaster was one of the demigods who allied with Kronos in the Titan War in The Last Olympian. He was sent into exile after the Titan War after refusing to stay at Camp Half-Blood. He claims to have led his siblings to their deaths during the war against the Olympians. He has several magical powers, which he channels through spells and magic writings.
- Alice Miyazawa – A daughter of Hermes. She is a close friend of Julia, and the two are never far from one another. Chiron states that she and Julia have taken over the Stoll brothers' knack for mischief, following Travis' enrollment on college and Connor's sudden reservement that it caused. The two girls harbor a crush on Apollo.
- Austin Lake – A teenage son of Apollo, an accomplished African-American musician who specializes in jazz saxophone. His mother, Latricia Lake, is a music professor at Oberlin College in Oberlin, Ohio whose music theory class Apollo once took. He is mentioned in The Last Olympian, where he is seen fighting alongside his brothers and sisters of the Apollo Cabin. He serves as a major character in The Hidden Oracle, where his and Kayla's abductions in the woods by Nero prompt Apollo to rescue them. Austin's inherited talents are primarily musical.
- Bianca di Angelo – A twelve-year-old daughter of Hades and the older sister of Nico di Angelo. Percy, Annabeth, Grover, and Thalia rescue her and Nico along with the help of the Hunters of Artemis from Westover Hall and the manticore Dr. Thorn. She becomes a Hunter of Artemis, whom she attempts to rescue in The Titan's Curse, alongside Percy Jackson, Grover Underwood, Thalia Grace, and Zoë Nightshade. She sacrifices herself to save the group from a mechanical prototype of Talos. For a while, this causes Nico to be mad at Percy but Nico has a secret crush on Percy which is mentioned in the House of Hades when Jason and Nico meet Cupid. Nico tries to summon Bianca from the dead many times but only meets her when Percy comes. In The Battle of the Labyrinth, Bianca Later in The Son of Neptune, she tries for rebirth on the Isle of the Blest.
- Billie Ng – Billie is a daughter of Demeter. In The Hidden Oracle, Billie is the only demigod of the Demeter cabin left in the winter season after the disappearance of her counselor, Miranda, until the arrival of Meg. She points out Meg's parentage during her claiming, in which a sickle and grain, symbols of Demeter, glow above her head.
- Bobby – Bobby is a caregiver of Camp Jupiter's war elephant Hannibal, first mentioned in The Son of Neptune. His Olympian parent is unknown.
- Butch – Butch is the head counselor of the Iris cabin at Camp Half-Blood. He and Annabeth are the ones who bring Jason, Piper, and Leo to the camp at the beginning of The Lost Hero. He is bald and muscular, with a tattoo of a rainbow on his upper arm.
- Castor – A son of Dionysus and the twin brother of Pollux. He is killed in The Battle of the Labyrinth when he was stabbed by a demigod allied with Kronos.
- Cecil Markowitz – A son of Hermes. In The Blood of Olympus, he is a part of the team sent to sabotage Camp Jupiter's onagers. In The Hidden Oracle, Cecil is the first to kidnapped by Nero and strapped to a crucifix to be sacrificed to burn the Grove of Dodona, although Apollo and Meg manage to save him.
- Charles – A son of Hephaestus and the head counselor of the Hephaestus cabin before he died and was replaced by Jake Mason. Like his father, he is a master smith. He is African American. He was in a relationship with Silena Beauregard, a daughter of Aphrodite, and is described as Mrs. O'Leary the hellhound's best friend next to Percy. He dies during an assault on the Princess Andromeda with Percy in the beginning The Last Olympian, around the age of 18. He had plans to attend NYU in the fall.
- Chiara Benvenuti – Chiara is a daughter of Tyche. She is Italian and indulges in the language when she curses, which Apollo understands much to his dismay. She has a rivalry with Damien, but is shown to be close friends otherwise. Apollo has more than once expressed his interest on her, though he does it with Damien also.
- Chris Rodriguez – The son of Hermes. He is often described as wearing a bandana around his head. Chris had joined Kronos and the Titans, but was turned insane by the ghost of Minos while on a mission in the Labyrinth. Clarisse finds him and brings him to Camp Half-Blood, where Dionysus restores his sanity. Chris later has a relationship with Clarisse. In the film adaptation, Chris is played by Grey Damon.
- Clovis – Clovis is the lead counselor of the Hypnos cabin. In The Lost Hero, Annabeth consults him regarding Jason's memory loss. In The Blood of Olympus, Nico Di Angelo sends a dream message to him to contact Thalia Grace.
- Connor Stoll – Connor and his brother Travis serve as lead counselors of the Hermes cabin after Luke's departure. The Stolls are known to be crafty and mischievous, like their father. They are tall and thin, with stringy brown hair. Both survive the Titan war. In The Hidden Oracle, Connor becomes the sole counselor due to Travis attending college, something that he still has not gotten over with. He picks on Meg after the latter pokes him in the eyes.
- Dakota – A son of Bacchus at Camp Jupiter, Dakota has an addiction to extra-sugary red Kool-Aid. He is both a centurion of the Fifth Cohort and a senator. Dakota is often on a sugar high, especially when stressed; in moments of clarity, however, he proves himself a capable leader.
- Damien White – Damien is a son of Nemesis. He has a heated rivalry with Chiara Benvenuti, although Apollo hints that the two are in a relationship at the end of The Hidden Oracle.
- Drew Tanaka – The lead counselor of the Aphrodite cabin, succeeding Silena, in The Lost Hero. She bullies and controls her cabin members with her power of charmspeak, leading Piper to successfully challenge her for the lead counselor position. She is also mentioned in The Serpent's Shadow of The Kane Chronicles as someone Sadie hates.
- Ellis Wakefield – Ellis is a son of Ares. In The Hidden Oracle. he is the second demigod to be kidnapped by Nero in the woods of Camp Half-Blood. Apollo later frees him and the others.
- Ethan Nakamura – A son of Nemesis, Ethan fights with Kronos and the Titans but begins to rethink his position. In The Last Olympian, he learns Percy's Achilles weak spot, but instead of killing him, Ethan turns on Kronos. However, his attack fails and Kronos kills him. Before he falls to his death 500 feet from Olympus, Ethan tells Percy that none of the bad blood that led to the war would have been caused if the minor gods had thrones on Olympus.
- Georgina – A daughter of Apollo who was adopted by Hemithea and Josephine and raised at the Waystation. At age seven, she started to show signs of her father's powers when the Oracle of Trophonius entranced her. She was kidnapped by Commodus before the events of The Dark Prophecy. Apollo frees her and realizes that she might be a daughter he does not know about.
- Gwendolyn – A centurion of the Fifth Cohort at Camp Jupiter. Gwendolyn is killed in The Son of Neptune but comes back to life because of Thanatos's capture. Her return prompts Mars to appear at Camp Jupiter and explain the circumstances of Thanatos's absence. She retires as centurion the day after because she decided to attend the college in New Rome and was replaced by Frank Zhang.
- Harley – A son of Hephaestus, first seen in The Lost Hero. He is eight years old at the time of The Hidden Oracle, but very muscular. Harley has been trying to locate Leo, his older half-brother, with a magical beacon ever since his disappearance in the aftermath of the Second Gigantomachy.
- Holly and Laurel Victor – Holly and Laurel are a pair of sisters and daughters of Nike. As per their upbringing, they are very competitive and refuse to be made second, hence why they are placed as co-counselors of the Nike's cabin, otherwise, as Kayla puts it "they would've taken over the camp by now and proclaimed a dictatorship". Apollo describes them as looking like the "gorgeous, ferociously athletic African nymphs" that he and Artemis used to hang out with at Lake Tritonis.
- Jacob – Jacob is the legion Aquilifer of Camp Jupiter. His godly parent is unknown.
- Jake Mason – Jake becomes the head of the Hephaestus cabin after the death of Beckendorf in The Last Olympian. He is severely injured during the Hepheastus's cabin's attempt to tame the bronze dragon later named Festus. In The Lost Hero, he steps down and gives the lead counselor position to Leo, after Leo finds Hephaestus's bunker in the woods.
- Jason – Not to be confused with Jason Grace or the mythical Jason, he is a demigod briefly mentioned in The Titan's Curse, being instructed by Thalia to team with Silena Beauregard and Laurel during capture the flag. His godly parent is unknown.
- Julia Feingold – A daughter of Hermes. Like her best friend, Alice, she harbors a crush on Apollo.
- Katie Gardner – The head counselor for Demeter's cabin at Camp Half-Blood after the war with the Titans. Katie strongly dislikes the Stoll brothers, who once put chocolate Easter bunnies on the Demeter cabin's grass roof.
- Kayla Knowles – A daughter of Apollo first mentioned in The Last Olympian carrying out the orders of Michael Yew. She is a major character in The Hidden Oracle, and is abducted by Nero. Kayla's mortal father is a Canadian archery coach named Darren Knowles. Kayla's inherited gift is archery.
- Lacy – Lacy is a daughter of Aphrodite who befriends Piper in The Lost Hero. She also appears in The Kane Chronicles. Lacy and Drew Tanaka appear in the Kane Chronicles, where Lacy is familiar with main character Sadie Kane.
- Larry – A senator at Camp Jupiter and a member of either the First or Second Cohort.
- Laurel – Laurel is only mentioned in The Titan's Curse. Because of circumstances around her mention, she may be a daughter of Aphrodite.
- Lee Fletcher – Lee was the head of Apollo cabin. He leads a team to attack a dragon threatening the camp. He is killed by a giant in The Battle of the Labyrinth.
- Lavinia Asimov - Lavinia is the daughter of Terpsichore, Muse of Dance, and likes to hike. She is promoted to centurion at the end of The Tyrant's Tomb.
- Leila – Leila is a daughter of Ceres and a centurion of the Fourth Cohort. In The Blood of Olympus, she and the rest of her cohort defect to Reyna's side once the latter arrives at Long Island.
- Lou Ellen – Lou Ellen is a daughter of Hecate in The Lost Hero. She is known for playing magical tricks on fellow campers.
- Malcolm Pace – Malcolm Pace is the assistant counselor of the Athena cabin under Annabeth Chase.
- Michael Kahale – A son of Venus and a centurion of the First Cohort. He is described as a fearsome Hawaiian despite being the son of a love goddess. As he is sponsored by Octavian, he remains loyal him despite his reservations of Octavian's decisions. In The Blood of Olympus, he reluctantly follows Octavian's order to attack Camp Half-Blood, but later leaves him to his fate when the latter ignites an onager with his feet being tangled with it.
- Michael Varus – A son of Janus and a former praetor of Camp Jupiter in the 1970s. He was killed by Alcyoneus during an expedition in Alaska and the eagle of Camp Jupiter was stolen with him. This tarnished the reputation of Varus' cohort, the Fifth, which was not recovered until Jason's promotion to praetor over three decades later. Varus' ghost appears to attack Percy in The Son of Neptune and again in The Blood of Olympus where he confronts Jason with his mother's mania and then mortally wounds him with an imperial gold sword.
- Michael Yew – Michael Yew succeeds Lee Fletcher as head of the Apollo cabin. He is described as very short, with a face that reminds Percy of a ferret. In The Demigod Files, in an interview with Clarisse, she mentions that she would want to pulverize Michael, thus stating that they are enemies. He is an excellent archer like most of Apollo's children and uses sonic arrows which were given to him by his father. He was presumed killed after leading a group of demigods in the fight against Kronos's army; Percy found his bow, but not his body.
- Miranda Gardiner – Miranda is second in command of the Demeter cabin in The Lost Hero. She assumes the head counselor's duties in the winter when Katie Gardner hibernates. In The Hidden Oracle, Miranda is the third to be kidnapped during Nero's spree in luring Apollo, which greatly disturbs Chiron due to her important status as counselor, though Apollo manages to rescue her. She is dating Sherman.
- Mitchell – Mitchell is a son of Aphrodite who is a friend of Piper in The Lost Hero.
- Nyssa Barrera – Nyssa is a daughter of Hephaestus. She meets Leo in The Lost Hero. She is mentioned on several occasions in the beginning and end of The Lost Hero. She also helps plan out Harley's Three-Legged Death Race in The Hidden Oracle.
- Olujime – Olujime, also known as Jamie, is a demigod under Commodus in The Dark Prophecy. He is a Nigerian student who attends accounting class at Indiana University and joined Commodus to pay for his education. After Apollo frees him, Olujime assists him in the defense of the Waystation. His wrestler-like appearance attracts the attention of Apollo, who to his dismay later finds out that Olujime already has a girlfriend. His status as a demigod is unique in the series, as he does not have connections to the established worlds of Greco-Roman, Egyptian, and Norse; instead, he channels his Yoruba heritage, from which he inherited electrokinesis, and also practices the Yoruba and Hausa martial arts Gidigbo and Dambe. His existence makes Apollo suspect that there may be another pantheon of African gods beyond the Sahara.
- Paolo Montes – A son of Hebe. He is from Brazil and is only able to speak Portuguese, although he understands English. He is able rejuvenate himself after particularly serious injuries, an ability which he inherited from his mother.
- Pollux – A son of Dionysus and the twin brother of Castor. He survives the war against the Titans, though his brother dies in The Battle of the Labyrinth.
- Pranjal - A son of Asclepius who works as Camp Jupiter's healer. In "The Tyrant's Tomb," he and Meg gather Buster's horn shavings as one of the ingredients for a medicine to heal Apollo's stomach cut.
- Sherman Yang – A son of Ares who was left in the care of his cabin as Clarisse, the counselor, is attending university. He marks Meg for target after the latter kicks him in the crotch, together with Connor. Like the other children of Ares, he is easily provoked. He is dating Miranda.
- Silena Beauregard – The head of the Aphrodite cabin for most of the Percy Jackson & the Olympians series. She is kind to Percy and befriends Clarisse La Rue after giving the other girl advice about her first relationship. She served as a spy for Kronos within Camp Half-Blood, but wanted to quit when her actions led to the death of her boyfriend Charles Beckendorf. Luke Castellan blackmails her into continuing as a spy. In The Last Olympian, she redeems herself by disguising herself as Clarisse and leading the Ares cabin into battle against the Titans. She dies a hero's death and is given a funeral at camp. In The Lightning Thief musical, she is portrayed by Carrie Compere.
- Travis Stoll – Travis and his brother Connor serve as lead counselors of the Hermes cabin after Luke's departure. The Stolls are known to be crafty and mischievous, like their father. He and his brother survive the Titan war. In The Hidden Oracle, he is shown to have gone to college, leaving his brother at camp.
- Valentina Diaz – A daughter of Aphrodite and the only member of her cabin left during winter season in The Hidden Oracle.
- Will Solace – A son of Apollo who becomes the head of the Apollo cabin after the death of Michael Yew during the second Titanomachy. He is a native of Austin, Texas, the son of an alt-country singer named Naomi Solace. He was introduced in The Last Olympian, where Annabeth is hurt and he uses his father's healing gift to help cure Annabeth. In The Blood of Olympus, Will is revealed to possess the ability to produce sonic waves in addition to his healing-related gifts. At the end of the series, it is implied that he begins a relationship with Nico di Angelo. He refers to him as his boyfriend in The Hidden Oracle, after helping heal Lester.
Historic demigods
- Adolf Hitler – A son of Hades and the chancellor of Nazi Germany. He is mentioned as one of the demigods of the Big Three who caused World War II, which resulted in the Pact of the Big Three.
- Alfred Hitchcock – The son of an unknown god. Alfred is mentioned when Percy Jackson and Will Solace arrive at the Plaza Hotel. It says that the Plaza attracted a lot of famous demigods over the years, such as the Beatles and Alfred Hitchcock.
- Amelia Earhart – The daughter of an unknown god. In The Sea of Monsters, Annabeth Chase mentions Amelia when talking to Circe. She was among the list of great female heroes. In The Lost Hero, Aeolus mentions that he knocked Amelia Earhart out of the sky and that the gods still pester him about it while talking to Jason Grace, Piper McLean, and Leo Valdez in his fortress.
- Archimedes – Archimedes is the son of Hephaestus, credited with the creation of many modern machines and an accurate approximation of pi. He is in modern times considered as one of the most well-known and one of the greatest of Hephaestus' children. It is the wish among many of Archimedes' modern-day siblings to find the lost works of Archimedes. During the Second Punic War, Archimedes was killed by a Roman guard working for General Marcus Claudius Marcellus who had given specific orders not to harm Archimedes. While searching for Nico di Angelo with Frank Zhang and Hazel Levesque in Rome as seen in The Mark of Athena, Leo Valdez recovered the lost works of Archimedes. He uses them to destroy the eidolons, possessive spirits working for Gaea. He planned to take them to Bunker 9 at Camp Half-Blood to study them further. With Archimedes' works, Leo hoped to save Camp Half-Blood from the Roman forces from Camp Jupiter.
- Banastre Tarleton – A demigod son of Bellona who participated in the Battle of Waxhaws. According to Reyna, Tarleton ignored the Colonial leader Abraham Buford's white flag and his forces massacred Buford's men. It is also mentioned that he was one of many Roman demigods who fought for the British during the American Revolution while the Greeks fought for the colonists.
- Blackbeard – The son of Ares, who was a notorious English pirate during the early 18th century. Instead of dying in his famous last stand, his ship landed on Circe's island where he and his crew were turned into guinea pigs for several hundred years. In The Sea of Monsters, Edward Teach is seen in guinea pig form. While on a quest, Annabeth Chase used Hermes' multivitamins to turn all of the guinea pigs back into humans. Along with his crew, he began to chase after Circe while Percy and Annabeth escaped with their pirate ship, the Queen Anne's Revenge.
- Franklin D. Roosevelt – The former President of the United States, who was mentioned by Bianca di Angelo in The Titan's Curse when she was trying to name the previous president due to her long period of time in the Lotus Casino.
- Frederic Bartholdi – The son of Athena who designed the Statue of Liberty. In The Demigod Files story titled The Stolen Chariot, Percy Jackson mentions Frederic Bartholdi to Clarisse La Rue. According to what Annabeth Chase had told Percy, Bartholdi designed the Statue of Liberty as a representation of his mother Athena.
- George Washington – A son of Athena and is the 1st President of the United States. In The Lightning Thief, George Washington is mentioned in the book as one of the few famous and successful demigods who survived outside of Camp Half-Blood and is depicted in one of the works displays during the Camp Half-Blood fireworks.
- Harriet Tubman – A daughter of Hermes and an abolitionist spy. In The Battle of the Labyrinth, Chiron states that Harriet once used many clear-sighted mortals on the Underground Railroad hinting that the Underground Railroad may have utilized the Labyrinth to help transport escaped slaves.
- Harry Houdini – The son of an unknown god who is a famous magician and escape artist, perhaps implying that his father was Hermes. It is mentioned in The Lightning Thief that he, Orpheus, and Hercules have each been able to escape from the Underworld. A Nereid said that Houdini "could escape even the depths of Tartarus."
- Jack London – The son of Mercury and author of Call of the Wild. He was mentioned in The Lost Hero as the one who built the Wolf House where Lupa judges the newly arrived demigods to see if they are worthy of being trained at Camp Jupiter.
- Joshua Lawrence Chamberlain – The son of an unknown god and a soldier in the American Civil War. In The Sea of Monsters, Chamberlain is mentioned by Chiron when talking to Percy Jackson after having rescued him and his friends from the Princess Andromeda.
- Thomas Jefferson – The 3rd President of the United States and the writer of the Declaration of Independence. In The Battle of the Labyrinth, Thomas Jefferson is mentioned to be among the rotating members of the Judgement Pavilion where he is assigned to judge where Daedalus will be sent to after his death.
- William H. Seward – The son of Hebe and a former Governor of New York. During the Battle of Manhattan in The Last Olympian, Annabeth Chase activated a statue of William H. Seward in Madison Square Park. It was the first statue she activated. It was a celestial bronze statue on a red marble pedestal. The William Seward statue was sitting on a chair, legs crossed, wearing an old-fashioned suit and a bow tie and long coattails. Books were piled under his chair, and he held a writing quill in one hand, big metal sheet of parchment in the other. The statue was one of many that Daedalus had created, to either attack or defend the Olympian gods, depending on which he needed to do to survive. He continued waking the other automatons as he was instructed to do.
- William Shakespeare – The son of Apollo, and one of the rotating members of the Judgement Pavilion.
- William Tecumseh Sherman – A son of Ares who fought in the American Civil War. In The Mark of Athena, William Sherman was mentioned by Coach Hedge when he and the seven arrived in Atlanta calling him Frank Zhang's half-brother and mistaking the son of Mars as Greek.
Legacies
- Bryce Lawrence – A legacy of Orcus. In The Blood of Olympus, Bryce is seen by Nico di Angelo in a dream. Despite being banished from Camp Jupiter by Reyna years ago for having killed his own centurion, Octavian allows him to return turning a blind eye to his cruelty towards the rest of his fellow cohort when he first joined the legion. He is given his probatio necklace and is assigned to the Fifth Cohort. In South Carolina, Bryce overhears Reyna's story of killing her father, and tries to capture her and take her to Octavian to charge her with the crime of patricide. He then is turned into a ghost by Nico and forced into the Underworld.
- Emily Zhang – Frank's mother, a Canadian Forces soldier who died in Afghanistan. She is descended from Periclymenus, which imbues her with the ability to shapeshift.
- Grandma Zhang – Emily's mother, also with her family's gift. She believes Frank should spend more time studying his Chinese heritage.
- Julia – A little girl who is the descendant of an unspecified god. In The Son of Neptune, she works as Terminus' helper at the security checkpoints at the New Rome town line. She often hides playfully underneath Terminus' statue base. Her parents died in "The Tyrant's Tomb" and Terminus adopted her in the end of the book.
- Octavian – Octavian is ambitious and cunning. He describes himself a descendant of Apollo in The Son of Neptune but Rachel calls him "son of Apollo" in The Mark of Athena. He reads the auguries for Camp Jupiter. After Jason Grace disappears, he campaigns to succeed to Jason's position as praetor. He is suspicious of the amnesic Percy Jackson when he arrives at Camp Jupiter, deducing he is a Greek demigod, rather than Roman by calling him graceus, the Latin for "greek". Mocking him and attempting to undermine his quest. When demigods from Camp Half-Blood arrive at Camp Jupiter, Octavian declares the Greeks invaders and urges the Romans to fight them off, believing the Greeks to be in league with Gaea. His warmongering escalates further in The House of Hades where he violates direct orders from Reyna not to attack Camp Half-Blood after leaving for her quest to get the Athena Parthenos back to Long Island, leaving him in command of the Legion. He is thin and blonde. He is also said to "look eighteen but could probably pass as younger." He dies in The Blood of Olympus where he launches an onager attack on Gaea during her defeat. Will Solace and Nico Di Angelo fight him many times but he dies when his foot gets tangled in the launching rope and he is launched along with the payload and dies in the explosion made by Leo Valdez to defeat Gaea. As his effort may have helped defeat Gaea, Octavian is hailed as a hero and his true actions covered up.
Mythological figures
- Achilles – The son of Thetis and Peleus. The ghost of Achilles appears briefly in The Last Olympian, warning Percy about the Curse of Achilles.
- Agamethus – The son of King Erginus and mortal half-brother of Trophonius. He was decapitated by Trophonius to spare the latter from being captured following a disastrous attempt to steal the riches of King Hyrieus. His headless ghost resurfaces to deliver baby Georgina to Hemithea and Josephine at Waystation and later becomes a constant visitor of the sanctuary. Lacking a head, he speaks by arranging the letters of Magic 8 Ball.
- Charon – Charon is the ferryman who carries the dead across the River Styx to the underworld. Percy and his friends meet him in The Lightning Thief. He also states he does not like being confused with the centaur Chiron. He likes Italian suits. In the film adaptation, Charon is played by Julian Richings. In the musical, Charon is portrayed by Carrie Compere.
- Chrysaor – A half-giant who is the son of Medusa and Poseidon, the brother of Pegasus, and the father of Geryon. He is first mentioned in The Last Olympian when Percy and Annabeth go to see the Oracle of Delphi in the attic of the Big House. A pair of fuzzy dice is said to have been stolen from his car. In The Mark of Athena, Chrysaor and his crew attacked the Argo II in the Mediterranean with the intent to sell Piper and Hazel to Circe, kill Jason, and then give Annabeth and Percy to Gaea. Chrysaor battles Percy on the deck of the Argo II. Once Chrysaor's crew abandon him, Percy surround him. Chrysaor is knocked off the Argo II by Frank and Percy and Chrysaor falls into the sea. A pair of fuzzy dice stolen by a demigod named Gus from Chyrsaor's Honda Civic are found in the Big House attic in The Last Olympian.
- Circe – Circe ran a magical beauty boutique in the Sea of Monsters, where she went by the alias of "C.C.". While she treated females at her spa, she turned males into guinea pigs. When Percy was turned into a guinea pig, Annabeth used multivitamins from Hermes to restore him, and together they defeated Circe. In The Heroes of Olympus series, it is revealed that Circe employed Reyna and Hylla after they left Puerto Rico and treated them nicely, at least until the pirates were freed and proceeded to capture the sisters.
- Daedalus/Quintus – Architect of the Labyrinth, Daedalus is the son of Athena and the father of Icarus. He killed his nephew Perdix but escaped eternal punishment by casting his soul into automatons. Athena branded him with a murderer's brand in the shape of a partridge. In The Battle of the Labyrinth, Daedalus appears under the alias of a Camp Half-Blood worker named Quintus. Percy and Annabeth convince him to use his technical genius to help defeat the Titan army in the Labyrinth. He then accepts death, willing to Annabeth his laptop filled with thousands of years of notes and ideas. In death, he becomes the Underworld's architect and is allowed to visit Icarus and Perdix on weekends.
- Eurytion – A son of Ares who works on Geryon's ranch. He appears in The Battle of the Labyrinth and helps Percy and Annabeth locate Hephaestus.
- Halcyon Green – A son of Apollo gifted with prophecy and under "house arrest" for revealing to a young woman her fate. He gives his life to save Luke Castellan and Thalia Grace from the Leucrotae and his burning mansion in The Diary of Luke Castellan.
- Heracles/Hercules – A famous Greek hero, and the son of Zeus and Alcmene. Following his death, Zeus brought him up to Mount Olympus to live with him and he is engaged to Hebe. Heracles was mentioned but did not appear in the first book series, usually when monsters that he had fought show up to trouble Percy. In The Titan's Curse, it is revealed that Zoë Nightshade helped Heracles steal the Apples of the Hesperides and gave him a magical sword Riptide which he had forgotten to return, leaving her to be disowned by her sisters and him giving her no credit for her help. Hercules appears in The Mark of Athena where he was tasked by Zeus to guard the Pillars of Hercules and issues Piper and Jason a quest for permission to enter the Mediterranean Sea.
- Hyacinthus – Hyacinthus was a beloved lover of Apollo. The right for him was contested between Apollo and Zephyrus, and when the former refused to share, Zephyrus caused an accident that led to Apollo's accidental killing over Hyacinthus. His death is regarded by Apollo as one of his two greatest losses of his life, together with Daphne's petrification. Upon his death, Hyacinthus was reincarnated as hyacinth. To this day, Apollo is still haunted by visions of him.
- Irus – A beggar who ran afoul of Odysseus upon his return to Ithica. In The Blood of Olympus, Jason posed as Irus to get close to the ghosts of the Suitors of Penelope.
- King Midas – A king who possessed the golden touch which turned anything he touched to gold. He is among the people brought back to life by Gaea in The Lost Hero where his Golden Touch was restored upon him and his son Lityerses emerging from the Doors of Death. It has been mentioned that Midas has occasionally turned Lityerses to gold by mistake causing him to use the nearby lake to wash the gold off him. Jason, Piper, and Leo come to Midas's mansion in Omaha, Nebraska. He was initially polite before revealing his allegiance and turning Leo and Piper into solid gold. Jason fought back against Midas and Lityerses and managed to restore Leo and Piper to life.
- King Minos – A former king who becomes one of the judges of the Underworld. Nico consults him in The Battle of the Labyrinth, but Minos kidnaps Nico and tries to kill Daedalus, who constructed the Labyrinth for him. When Daedalus later ends up in the Underworld, Minos unsuccessfully tries to convince the other two judges to punish Daedalus.
- King Sisyphus – A former ruler of Corinth. He had committed violations of guest hospitality, seduced his niece, plotted to kill his brother, Salmoneus, and told the river god Asopus where Zeus had his daughter. His major crimes involved cheating death twice. The first where he tricked Thanatos into showing him how the chains worked causing Thanatos to be trapped until Ares freed him. The second time was when he complained to Persephone that his wife Merope did not give him a proper funeral and sent Sisyphus' spirit to the living. Even when Sisyphus did not want to return to the Underworld, he was forcefully dragged back there by Hermes. His punishment in The Fields of Punishment was to push a boulder up a hill. When it got close to the top, the boulder would roll back to the bottom and Sisyphus was condemned to begin again. He appears in The Demigod Files in the story titled The Sword of Hades when Percy and Nico asked his advice while Thalia pushes the boulder up the hill. He does not really help them much, but he does say that he helped someone else. He said that he told that other person to go see Melinoe. Therefore, Percy and his friends go to see Melinoe as Sisyphus begs for them to set him free from his punishment for being here was a minor set-back.
- King Tantalus – The spirit of a king from the Fields of Punishment who is the son of Zeus. He ended up there after killing his son Pelops, cutting him up, and serving him as food to the gods. His punishment in the Fields of Punishment was to stand under a fruit tree in the middle of a lake. When he tried to pluck the fruit to eat, the branches of the tree rose out of his reach and when he bent down to drink the water, the level would retreat. Tantalus became "tantalised" by having food and drink close to him, but unable to enjoy either. He becomes the activities director at Camp Half-Blood after Chiron is fired. He appears in The Sea of Monsters as a minor character. Even when hired as the activities director, he could not eat or drink as the food kept evading him. Tantalus is shown to hate Percy and his friends even more than he hates most half-bloods, yet shows favoritism to Clarisse, as when naming her hero when the camp was attacked by Colchis Bulls or when she wins the chariot race and throwing a banquet in her honor. When Tyson is brought to camp, Tantalus insults and makes fun of him even when Tyson is claimed by Poseidon. When the camp is attacked by a large flock of Stymphalian birds, Tantalus blames it on Percy, Annabeth, and Tyson's "bad chariot driving" despite that they were the ones who defeated the birds. At the end of the book, his curse is lifted by Dionysus just before he is sent back to the Underworld as he attempts to take some food along. None of the campers are sad to see him go.
- Lityerses - The son of King Midas who is nicknamed "Lit." In The Lost Hero, he and Midas emerged from the Doors of Death. After King Midas turns Leo and Piper to gold, he has Lityerses fight Jason before Midas can turn him to gold. After Jason defeats Lityerses, King Midas tries to help him only to accidentally turn him to gold. After throwing a rug over Lityerses, Jason summoned a thunderbolt that caused rain to come down on those who had been turned to gold. In The Dark Prophecy, Lityerses is freed from his golden from by Commodus and goes to work for him. He later defects to the side of the Waystation's inhabitants.
- Medea – A sorceress and a granddaughter of Helios. Jason, Piper, and Leo encounter her in The Lost Hero, where she runs a mall in Chicago under the name "M". She becomes enraged upon learning Jason's name which he shares with her former husband, the hero that recovered the Golden Fleece who left her. Her magic causes Jason and Leo to become hostile to one another. Realizing Medea is an agent of Gaea, Piper brings them to their senses and leads their escape before Medea can do anything else to them by blowing up the mall and killing her again. In The Burning Maze, Medea returned where she is now working for Caligula. When she engages Meg in a charmspeak battle, she announces her plans to take Apollo's essence, combine it with her grandfather's leftover power, and make Caligula the new God of the Sun. Medea later appears in the throne room of Caligula asking him to perform the ritual after she trapped Jason and Piper in a tornado prison. When Apollo stabs himself, Medea and Caligula rush to perform the ritual before he dies. Her being focused on the ritual weakened the tornado prison enabling Piper to punch Medea. When Apollo reaches Herophile's holding area, Medea appears and prepares to extract Apollo's essence. Piper saves Apollo by stabbing Medea and pushing her into Helios' flames.
- Muses – The immortal daughters of Zeus and the Titan Mnemosyne. They inspired and presided over several creative arts. In The Lightning Thief, the Muses performed on Mount Olympus at the time when Percy returns Zeus' Master Bolt. As the gods celebrate, the Muses play music that sounds like anything you want, so no one argues about the music. In The Titan's Curse, the Muses perform their music after the Gods decide not to kill Percy and Thalia. According to Percy, everybody hears the music they only want to hear, like classical for the gods and hip hop for the younger demigods. In The Last Olympian, a few Muses are shown playing some tunes on Olympus. Their hearts were not into it because of Kronos' attack on Mount Olympus while the Gods were out fighting Typhon.
- * Calliope – The muse of Epic Poetry.
- * Clio – The Muse of History.
- * Erato - The Muse of Love Poetry.
- * Euterpe – The Muse of Music.
- * Melpomene – The Muse of Tragedy.
- * Terpsichore – The Muse of Dance.
- * Thalia – The Muse of Comedy.
- * Urania – The Muse of Astronomy.
- Narcissus – A hunter who was renowned for his beauty and disdained those that had loved him. Nemesis puts a spell on him that causes him to fall in love with the reflection of himself in the water where he dies upon not being able to leave his own reflection. In The Mark of Athena, Narcissus is encountered by Hazel Levesque and Leo Valdez at the Salt Lake in Utah where the demigods are looking for the Celestial Bronze which is needed to help repair the damaged Argo II. When Narcissus realizes that Hazel and Leo have managed to steal his bronze plate which he uses to be able to admire his own reflection, he and a mob of nymphs runs after them trying to kill them.
- Oracles - The Oracles are both beings and places that can give prophecies in Greek mythology. There are five of them. Four Oracles are associated with Apollo.
- * Oracle of Delphi – Apollo's Oracle of Delphi resides in the mummified remains of its host, until its power was transferred to Rachel Dare in The Last Olympian. At the end of World War II, the oracle issued the Great Prophecy, saying a child of the Big Three would determine the preservation or destruction of Olympus. This caused those gods to form a pact not to father more demigods. In Percy Jackson: Sea of Monsters, the Oracle of Delphi is voiced by Shohreh Aghdashloo. In the musical, she is portrayed by Carrie Compere.
- * Trophonius – Son of Apollo and half-brother of Agamethus, he and his brother's attempt to steal the riches of King Hyrieus ended with Trophonius reluctantly decapitating Agamethus to save himself, despite him having begged Apollo to save them. Later, he became guardian of an oracle which bears his name, reputedly the oracle that would drive its seekers into insanity unless proper rituals are conducted. Regardless of his antagonism to Apollo due to his predicament, he asks his father to destroy the Oracle and himself, so Commodus would not be able to access it again.
- Pasiphaë – A Greek sorceress and a daughter of Helios who appears in The House of Hades. She is resentful of the gods for punishing her by giving birth to Minotaur, while her husband, Minos, who caused the problem in the first place, enjoys the right as a judge in the Underworld for being Zeus' son. She is allied with the giants and does a battle of sorcery with Hazel, who manages to trick her into entering an imaginary trapdoor in the Labyrinth.
- Phineus/Phineas – A blind seer who appears in The Son of Neptune. Percy Jackson finds him in Portland where the Harpies are trying to steal his food. Before he dies from Gaea making him choose the poisoned gorgon's blood from the offer Percy gave him, he reveals to Percy the location of Alcyoneus' camp.
- Procrustes/Crusty – The son of Poseidon who is depicted as a half-giant in this franchise. He is a rogue thief and blacksmith who was previously defeated by Theseus. Procrustes appears in The Lightning Thief as "Crusty", a Los Angeles mattress store owner. He traps Annabeth and Grover on his beds and tries to stretch their spine. Percy defeats him by using Riptide on him.
- Sciron – A thief and son of Poseidon. He had previously fought Theseus in the past. In The House of Hades, Sciron and his giant turtle waylaid the Argo II on the coast of Croatia. Like his fight with Theseus, Hazel defeated Sciron by pushing him off the cliff where he was gobbled by the Giant Sea Turtle.
- Suitors of Penelope – Men who competed to become the next wife to Penelope when they believed that she became a widow when Odysseus was fighting in the Trojan War. When Odysseus returned, his disguised appearance spoke to Penelope to hold a contest where the Suitor that can string Odysseus' bow will become her new wife. When Odysseus won the contest, he sheds his disguise and kills the Suitors with the help of Telemachus and Philoeteus. In The Blood of Olympus, Jason, Piper, and Annabeth encounter the ghosts of the Suitors of Penelope on Ithica where they are now allied with Gaea.
- * Antinous – One of the Suitors of Penelope.
- * Eurymachus – One of the Suitors of Penelope.
- Theseus – A hero who is the son of Poseidon and younger than Percy had assumed. When Nico was trying to summon Bianca in The Battle of the Labyrinth, he ended up summoning the spirit of Theseus.
Other Greco-Roman beings
Greco-Roman humanoids
Many of the beings and creatures of Greco-Roman myths are humanoid—in other words, they possess both the intelligence and some of the physical features of humans. The vast majority of these creatures are friendly, such as nymphs and centaurs. Unlike the majority of Greek creatures, these beings are also unquestionably sentient and tend to have larger roles in the novel series.- Agrius and Oreius – Humanoid bears that were a result of a union between a woman named Polyphonte and a bear due to the power of Aphrodite. They were also the great-grandsons of Ares due to Polyphonte being Ares' granddaughter. The two served as Luke's henchmen in The Sea of Monsters.
- Amazons – A tribe of female warriors who usually worshiped goddesses like Hera and Artemis. Some Amazons appear in The Son of Neptune where they are sent to their compound at Reyna's request. They also run the billion-dollar Amazon.com, which they use as a source of cover and revenue. Though they are often confused with the Hunters of Artemis, the Amazons are not misandrists and like men just fine; they are just a very matriarchal society in which their male spouses are made to work in manual labor while the Amazons work as administrators. In The Blood of Olympus, the Amazons collaborate with the Hunters of Artemis to protect Reyna from Orion, resulting in many casualties.
- * Doris – An Amazon who is loyal to Otrera. In The Son of Neptune, she and Lulu guarded Percy Jackson and Frank Zhang.
- * Hylla Ramírez-Arellano – The older sister of Reyna, the praetor of Camp Jupiter; she is 22 years old. She is a demigod daughter of Bellona and the Amazon Queen. She looks a lot like Reyna with beautiful, glossy black hair and black eyes, long lashes, and a scar on her forehead. She as her sister had the bearing of a swordswoman but stronger. Hylla wears a black suit with a golden belt. Reyna describes her sister as a "chameleon" because she is always changing. They have similar personalities but Hylla seems more funny and "chill". She was born in Puerto Rico and worked for Circe during the first series with her sister. She also spent a year living with pirates and winning the crew's respect. She had an awful childhood, basically she was always trying to protect her sister from their dad. Her father was in the army and the whole Ramírez-Arellano family was favored by Bellona. While worshiping her, Hylla's father falls in love with the idea of war and Bellona. They have the two kids together. Later, the father shows symptoms of PTSD. It turned out he had become a mania, or an insane soul with the worst qualities, and was no longer human. The mania knocks out Hylla, Reyna think she is dead and unknowingly kills her father, who was, technically, already dead. All that was left was the crazed and obsessed remnants of the soul. In The Blood of Olympus, the Amazon have been working with The Hunters of Artemis who kidnap Reyna and take her to an Amazon headquarters, where Hylla reunites with her sister. Orion breaks into the Amazon HQ and kills every Hunter and Amazon, but the girls escape to their old house, and try to defeat Orion without success. Hylla orders Reyna to leave because she had to stay in combat with the supervivients, hunters, and some Amazons. Though she is never seen afterwards, Orion later confirms that Hylla is still alive after battling him, much to Reyna's relief.
- * Kinzie – An Amazon who is the daughter of a nymph and is close and loyal to Hylla. She disarmed Percy and sent Frank flying across the room in The Son of Neptune. Kinzie also cornered Percy during the Feast of Fortuna and asked Percy out, though he declined. In The Blood of Olympus, Kinzie is killed by Orion.
- * Lulu – An Amazon guard who is loyal to Otrera. In The Son of Neptune, Lulu and Doris guarded Percy Jackson and Frank Zhang.
- * Otrera – A daughter of Euros and the first Queen of the Amazons who was originally killed by Bellerophon. In The Son of Neptune, she is revealed to be among those who emerged from the Doors of Death. She challenged Hylla for the title of Queen of the Amazons. When she planned to defeat Hylla, Otrera plans to have the Amazons help Gaea and the Giants destroy Camp Jupiter. Hylla manages to defeat Otrera twice until Thanatos is freed from the chains where he was trapped, making sure she would not rise from the dead and challenge her again.
- Arachne – A female weaver who was turned into a spider by Athena after she got angry when Arachne won in a weaving contest against her. In The Mark of Athena, Arachne appears as a spider-like monster who is the last obstacle for Annabeth's quest to the Athena Parthenos and is in collaboration with Otus and Ephialtes. Annabeth challenges Arachne to a weaving contest where Annabeth tricks Arachne into making monster-sized Chinese handcuffs which Annabeth places onto Arachne. When Annabeth states to Arachne that the Athena Parthenos will restore Mount Olympus, Arachne goes into a fit and brings down her chamber enough to open a chasm to Tartarus. As Arachne falls down into Tartarus, she manages to ensnare Annabeth at the last minute as she and Percy go down the chasm with Nico promising to meet them at the Doors of Death. In The House of Hades, Arachne ambushes Percy and Annabeth which ended with Percy using Riptide to defeat Arachne.
- Antaeus – A half-giant who is the son of Poseidon and Gaea. He was invincible as long as he maintained contact with the ground, so Percy defeated him by hanging him in the air with chains.
- Argus – A humanoid figure with eyes all over his body who works as a security guard at Camp Half-Blood. He rarely speaks as he is said to have an eye on his tongue. He cares for Hera a lot because she is his creator.
- Blemmyae - A race of headless people with their facial features on their chest.
- * Nanette - A Blemmyes who works for Triumvirate Holdings. In The Dark Prophecy, Nantette tries to arrest Apollo, Calypso, and Leo in the name of Triumvirate Holdings. Apollo tricks her into holding a bomb towards the Cave of Trophonius, where she meets her end.
- Cacus – A fire-breathing giant. In The Demigod Diaries story titled "Percy Jackson and the Staff of Hermes", Cacus had stolen Hermes' Caduceus. He later attacked Percy Jackson and Annabeth Chase. Annabeth hit Cacus with her metal claw and Percy killed Cacus with Hermes' Caduceus.
- Centaur – Half-man, half-horse creatures, often depicted as wild and drunk. Chiron is the only truly civilized centaur. Many of his kin are part of the Party Ponies. There are other centaurs who work for Gaea's army.
- * Chiron – A centaur with a white stallion body and a son of Kronos. He is the mentor of Percy Jackson and the activities director at Camp Half-Blood. In The Lightning Thief, he first appears, disguised as a Latin teacher at Percy's school. He uses an enchanted wheelchair to conceal his horse half. Chiron is played by Pierce Brosnan in the first film and by Anthony Head in the second film. In the musical, he is portrayed by Jonathan Raviv.
- * Horned Centaurs – A race of centaurs with horns sticking out of their heads and their horse half is palomino. These centaurs enjoy killing demigods. In The Son of Neptune, they attacked Camp Jupiter where most of them were either killed or have retreated.
- * Party Ponies – An extended family of rowdy centaurs who reside in the United States with chapters hailing from each respective state. They are key players in two major incidents in the series. In The Sea of Monsters, they go along with Chiron and rescue Percy from Luke during their duel on the Princess Andromeda. In The Last Olympian, they help Chiron and the others fight the major battle between the gods and the Titans.
- ** Larry – Member of the Party Ponies.
- ** Owen – Member of the Party Ponies.
- Cyclopes – A race of one-eyed giants who have four species as mentioned in The Lost Hero. The first group of Cyclopes are the Elder Cyclops who are the sons of Gaea and Ouranos where they alongside the Hecatonchires were imprisoned in Tartarus by Ouranos. They are friendly and help the gods ever since the Titanomachy when they were freed from their imprisonment. The second group of Cyclopes are the ones who are the children of Poseidon. Tyson is one of these. The third group of Cyclopes is the southern group who raise goats and live in caves. The fourth group of Cyclopes is the northern group who helped the Titans make weapons and are smarter than the southern group of Cyclopes. Some northern Cyclopes were seen fighting with Kronos' army in The Battle of Manhattan. In The Dark Prophecy, many Cyclopes were present at the rehearsal of Commodus' naming ceremony.
- * Grunk - A Cyclops that is loyal to Caligula. In The Burning Maze, he was seen by Apollo and Piper playing volleyball with some mortal mercenaries. Piper sings them a song in order to distract them so that they can get away.
- * Ma Gasket – A 12 ft. female cyclops of the Northern Cyclops faction who is the mother of Sump and Torque. She appears in The Lost Hero when Jason, Piper, and Leo visit her factory. In The Son of Neptune, Ma Gasket leads the Cyclopes in an attack on Camp Jupiter where she is defeated by Tyson.
- ** Sump – The son of Ma Gasket who appears in The Lost Hero.
- ** Torque – The son of Ma Gasket who appears in The Lost Hero.
- * Polyphemus – A 15 ft. cyclops of the Southern Faction. Percy Jackson and his friends encounter him on an island in The Sea of Monsters. He is shown to be blind and there was also a reference about Odysseus being responsible for blinding him under the alias of "Nobody". When Polyphemus tries to pray to Poseidon to get revenge on Percy for hurting him, Percy states that Poseidon is also his father. He later tried to eat them only for them to escape. In Percy Jackson: Sea of Monsters, Polyphemus is portrayed by Robert Maillet and voiced by Ron Perlman.
- Cynocephali - A race of dog-headed men that come from India. In The Blood of Olympus, Octavius obtained some Cynocephali from Triumvirate Holdings. In The Dark Prophecy, the Cynocephali are seen at the naming rehearsal held by Commodus as he prepares to invade the Waystation. In The Tyrant's Tomb, the Cynocephali are among the monsters used in Caligula's attack on Camp Jupiter.
- Echidna – Part woman, part snake. She is the wife of Typhon and the mother of Cerberus, Chimera, Hydra, the Nemean Lion, and Ladon as well as several others not in the series. She is first seen in The Lightning Thief as an old lady who owned a chihuahua which was actually Chimera in disguise. Echidna also detests that there is a marsupial that was named after her. She assisted Chimera in fighting Percy at the top of the St. Louis Arch. She and Chimera disappeared after Percy dove into the water.
- Empousai – Seductive shapeshifting women who are similar in appearance to vampires, but have one shaggy donkey leg and one bronze leg. Two Empusa pose as cheerleaders in The Battle of the Labyrinth. In The Last Olympian, an unnamed Empousai appears as part of the truce party along with Prometheus, Morrain, and Ethan Nakumura. She stated that she was among the things that was released from Pandora's pithos.
- * Kelli – An Empousai that poses as a cheerleader in The Battle of the Labyrinth. She was killed by Annabeth. In The House of Hades, Kelli is among the Empousai that make their way to the Doors of Death so that Kelli can get even with Percy. With the help of Bob the Titan, Percy and Annabeth defeat Kelli and the Empousai.
- * Seraphone – An Empousai who distrusts Kelli and fears Hecate. In The House of Hades, Seraphone is among the Empousai that make their way to the Doors of Death. When they attack Percy and Annabeth, Annabeth tricks the Empousai into believing that Kelli was useless and weak and that she was leading them all into danger. Annabeth tells them to follow Serephone as she was older and wiser. Hearing this made Serephone happy and declared that she was a leader. Kelli became angry and killed Serephone.
- * Tammi – An Empousai that poses as a cheerleader in The Battle of the Labyrinth. She was killed by Percy Jackson.
- Eurynomos - A ghoulish creature from the Underworld that is liked by Hades where anyone struck by its claws will die of a wasting disease. When a Eurynomos eats the flesh off a dead person, they rise as a skeleton warrior. In The Tyrant's Tomb, Lester and Meg are attacked by one when en route to Camp Jupiter. Before it can eat them and Jason's corpse, they are saved by Lavinia.
- * Caelius - A Eurynomos who is loyal to Tarquin. In The Tyrant's Tomb, Caelius mentions about Tarquin's upcoming attack on Camp Jupiter. He is beheaded by Hazel.
- The Fates – The personification of destiny and are controllers of the threads of life. In The Lightning Thief, Percy and Grover encounter them at an old-fashioned fruit stand. In The Last Olympian, the Fates take Luke's dead body away after the Second Olympian War. In The Blood of Olympus, the Fates are seen fighting their old enemy Thoon and killing him the same way they did back in the Gigantomachy.
- * Clotho – The Fate who spins the Thread of Life from her distaff onto her spindle.
- * Lachesis – The Fate who measures the Thread of Life with her rod.
- * Atropos – The Fate who cuts the Thread of Life and chooses the manner of the person's death.
- Faun – The Roman counterparts of satyrs. In contrast to Camp Half-Blood's helpful satyrs, the fauns are mostly beggars and are often used for amusement purposes.
- * Don – One of the Fauns that live at Camp Jupiter. In The Son of Neptune, Percy and Hazel run into Don who needs money for making up bad lies. When Percy asks why the Fauns aren't like the Satyrs, Don states that Fauns are free-spirited. In The Tyrant's Tomb, Don owed a favor to Lavinia.
- The Furies – Hades' chief servants and torturers and they personally searched for Hades's Helm of Darkness, believing that Percy had stolen it.
- * Alecto – Alecto acted as Percy's pre-algebra teacher Mrs. Dodds in the first book. She is Hades's main servant. In The Last Olympian, Alecto acted as the lawyer who rescued Nico and Bianca di Angelo from the Lotus hotel. In the film adaption, Alecto is portrayed by Maria Olsen. In the musical, she is portrayed by Sarah Beth Pfeifer.
- * Megaera – A Fury representing grudging.
- * Tisiphone – A Fury representing avenged murder.
- Germani – The Roman Emperor's elite bodyguards. They come from Germania and are described as 7 ft. and hulking with blond hair and snake tattoos. In The Burning Maze, it is revealed that Caligula uses Pandai and Strix because the Germani are responsible for his mortal death.
- * Alaric - A Germani who briefly worked as a prefect for Commodus. In The Dark Prophecy, Alaric was made a Prefect when Commodus believed that Lityerses wasn't being effective enough. After his failed strategy during the attack on the Waystation, Alaric was killed by Commodus.
- * Albatrix - A Germani that works for Commodus.
- * Gregorix - A Germani that works for Caligula and Commodus. In "The Tyrant's Tomb," he is seen with them during Caligula's Second Assault on Camp Jupiter.
- * Vincius and Garius - Also known as Vince and Gary, they hail from Batavia. Their names are Latinized as Nero cannot pronounce their original Germanic names.
- * Vortigern - A Germani that works for Commodus. In The Dark Prophecy, Nero instructed Vortigern and Marcus to take Meg to Commodus. After Meg got away, Commodus was not pleased with their failure and had Lityerses behead them with his sword.
- Geryon – In this series, Geryon is described as having a normal head, a face weathered and brown from years in the sun, slick black hair, a pencil-thin moustache, two beefy legs wearing a large pair of Levis and 3 chests wearing a different colored shirt: green, yellow and red. In The Battle of the Labyrinth, he is the owner of Triple G Ranch with Orthrus guarding the ranch. He gave Percy an apparently impossible task; cleaning out the stables of carnivorous horses, one of the Labors of Hercules. Percy managed to complete the task, but Geryon went back on his deal to let Percy's friends free and the two fought. Percy found Geryon a strong opponent, as Geryon's three hearts made him almost impossible to defeat. Percy defeated Geryon with a well placed arrow that went through Geryon's side hitting all three hearts at once, killing Geryon. In The House of Hades, Geryon had cursed Percy to feel the pain he had when Percy killed him. The Arai later told Percy about this. Percy later spotted Geryon among the characters awaiting their turn to go through the Doors of Death.
- Ghoul – The Ghouls serve as security guards in the Underworld and make a sound that is similar to bats. They escort the souls of the wicked to the Fields of Punishment as seen in The Lightning Thief when they take a preacher who had been scamming people there.
- Giant – Humanoid monsters of great stature and strength. Besides the Cyclopes and the Gigantes, there are different species of giants in Greek mythology.
- * Gegeines – Six-armed giants in leather loincloths who previously fought Jason and the Argonauts. They appear in The Lost Hero where they are summoned by Enceladus to fight Jason, Piper, and Leo.e of
- * Hekatonkheires – The Hundred-Handed Giants of incredible strength, superior even to the Cyclopes. They are taller than mountains and their arms are as thin as noodles. Like the Elder Cyclopes, the Hekatonkheires are the children of Gaea and Ouranos where they were hurled into Tartaus by Uranus. The Hekatonkheires and the Elder Cyclopes were later freed by Zeus where they helped him in the Titanomachy. In the film Percy Jackson: Sea of Monsters, a Hekatonkheires worked as a barista at a coffee shop with a harpy. Its appearance in the film was depicted as having eight arms when in the presence of demigods.
- ** Briares – A Hekatonkheires who was imprisoned on Alcatraz Island by Kampê in the fourth book. It is mentioned that his brothers Cottus and Gyges have faded because people have forgotten about them. When Tyson finds that Briares is too afraid to escape, he is heartbroken. At the end, Briares returns to help defeat Luke and the Titans. In The Last Olympian, Percy sees Briares helping Poseidon defeat the forces of Oceanus.
- * Hyperborean – Snow giants with blue skin and gray hair that come from Hyperborea. When wounded, the Hyperborean will bleed blue blood. They can freeze objects and people using their frosty breath. When defeated, the Hyperborean freeze into ice. In The Last Olympian, the Hyperboreans are on the side of the Titans. In The Son of Neptune, a group of peaceful Hyperboreans were seen in Anchorage, Alaska.
- ** Morrain – A Hyperborean who appeared in The Last Olympian. He was a part of a truce meeting. He wasn't seen taking part in the Battle of Manhattan and his current fate is unknown.
- * Laistrygonian – Muscular cannibal giants who were previously encountered by Odysseus. In The Sea of Monsters, three Laistrygonians serve as the brawn of Kronos's army. Three of them infiltrated Percy's school as visitors from Detroit and attacked the students with flaming dodgeballs. They were defeated by Percy, Annabeth, and Tyson. In The Battle of the Labyrinth, a Laistrygonian assisted Kelli the Empousai into capturing Percy, Annabeth, and Rachael where they were marched to Antaeus' lair. Two more Laistrygonians were seen in Daedalus' lair where they followed Minos and carrying Nico with them. When the Titan army made their way through the Labyrinth and attacked Camp Half-Blood, the Laistrygonians were among the monsters that took part in the attack. They were pushed back by the campers in Apollo's cabin and the Laistrygonians retreated when Grover unleashed the powers of Pan. In The Last Olympian, the Laistrygonians were seen in The Battle of the Labyrinth. When one Laistrygonian tried to attack Sally Jackson, she managed to shoot it.
- ** Joe Bob – A Laistrygonian.
- ** Marrow Sucker – A Laistrygonian.
- ** Skull Eater – A Laistrygonian.
- Gorgon – A female humanoid creature with snakes for hair. Anyone who looks at the face of the Gorgon Medusa turns to stone.
- * Medusa – The Gorgon who is the sister of Stheno and Euryale. Under the moniker of "Aunty Em", she attempted to lure Percy, Annabeth, and Grover into a false sense of security and turn them into stone statues as seen in The Lightning Thief. She is defeated and her severed head is mailed to the gods of Olympus as proof of the trio's courage. Percy's mom previously uses her head to turn Gabe Ugliano to stone. In the film adaptation, Medusa is portrayed by Uma Thurman.
- * Stheno – A Gorgon who is the sister of Medusa and Euryale. In The Lost Hero, she was mentioned to be among the characters who were brought back to life when the Doors of Death opened. Stheno is later found to be chasing Percy and is described by Percy as appearing as a dumpy old grandmother but with rooster feet and bronze boar tusk sticking out of the corners of her mouth.
- * Euryale – A Gorgon who is the sister of Medusa and Stheno. In The Lost Hero, she was mentioned to be among the characters who were brought back to life when the Doors of Death opened. Euryale is later found to be chasing Percy with her sister Stheno.
- Gray Sisters – Women who share one eye and one tooth. In The Sea of Monsters, Percy, Annabeth, and Tyson run into the Gray Sisters who are in the form of three taxi drivers. During the Gray Sisters' argument, Percy manages to grab their eye and demand the location of which they had mentioned. They tell him 30, 31, 75, 12 which Percy didn't understand. He however gave the eye to Wasp and they drop the three off at Camp Half-Blood. Later at the campfire, Percy figures out that the numbers were used for longitude and latitude which leads to the Sea of Monsters. In the film adaptation, the Gray Sisters are portrayed by Mary Birdsong, Yvette Nicole Brown, and Missi Pyle.
- Harpy – Winged spirits of sudden, sharp gusts of wind. They were known as the "Hounds of Zeus" and were dispatched by the god to snatch away people and things from the Earth. Sudden, mysterious disappearances were often attributed to the Harpies. There are three Harpies that were created by Zeus. They work in Camp Half-Blood as "the Cleaning Harpies" being allowed to eat any camper who stays in Camp Half-Blood past noon in the last day of the summer without completing their form or if the camper is caught sneaking out of their cabin at night. Percy Jackson refers to the "Cleaning Harpies" as if they were "crossbred with the dodo birds." The Harpies also cleaned the dishes with super-hot lava and are also good in mid-town traffic. In The Titan's Curse, it is shown that there are some Harpies that are on the side of the Titans. In the film Percy Jackson: Sea of Monsters, a harpy worked as a barista at a coffee shop with a Hekatonkheires.
- * Aello – A Harpy whose name means "storm swift." She is a member of Camp Half-Blood's "Cleaning Harpies."
- * Aeolus' Harpies - In The Lost Hero several unnamed harpies work for Aeolus. They construct a floor in the main studio for Jason, Leo, and Piper to walk on. Mellie does not like them because the harpies are mean sudden gusts, whereas the aurae are all gentle breezes.
- * Celaeno – A Harpy whose name means "the dark." She is a member of Camp Half-Blood's "Cleaning Harpies." Celaeno is also known as Podarge.
- * Ella – A Harpy who appears in The Son of Neptune. She has red hair and feathers, grey eyes, and a bony structure. She has extensive knowledge about the Romans and their culture. Ella is very valuable to the enemy side as she might have knowledge of several scrolls of prophecies. She has memorized a lot of books, and often recites a few prophecies from the Sybilline books that Octavian desperately wants. It is mentioned towards the end of The Son of Neptune, that Ella needed to be hidden from Octavian because of this important knowledge. She was one of the Harpies who was trying to torment the blind psychic Phineas. Near the end of the book, it is revealed that Tyson has a crush on Ella and that she has a crush on Tyson. Because of this, Ella remains with Tyson at Camp Jupiter.
- * Ocypete – A Harpy whose name means "the swift wing." She is a member of Camp Half-Blood's "Cleaning Harpies."
- Hunters of Artemis – A group of girls who gave up love in exchange for immortality and youthfulness. As their name implies, they are followers of Artemis in her hunts, though a lieutenant in chosen to lead them when Artemis is not around. Members are recruited both from mortals and demigods. They have a strong aversion to males and tend to regard them as disgusting and untrustworthy. However, their immortality will fade if they ever fall in love or "fall in battle". In battles, the hunters primarily use bows to attack. Zoë Nightshade serves as the group's lieutenant for over 2000 years, but after her death in The Titan's Curse, she is succeeded by Thalia Grace. In The Blood of Olympus, many members are massacred by the Gigante Orion while attempting to give Reyna time to escape from Puerto Rico.
- * Celyn – A hunter who appears in The Blood of Olympus. She is killed by Orion.
- * Naomi – A daughter of Hecate and another hunter who captures Reyna in The Blood of Olympus. She is killed by Orion.
- * Phoebe – One of the Hunters of Artemis, the best tracker among them. She is suspicious of boys. She appears in The Titan's Curse, The Lost Hero and The Blood of Olympus. In The Blood of Olympus, she is revealed to have looked about 14 and to have lived since Artemis first knew Orion. She eventually dies by the hands of Orion.
- * Zoë Nightshade – Zoë was the leader of the Hunters of Artemis. She appears in The Titan's Curse. She was a daughter of Atlas and the sea goddess Pleione. She crafted Riptide, but lost it to Hercules. She was once one of the Hesperides, but she was disowned by her family for helping Hercules. In The Titan's Curse, she is killed by Atlas. In remembrance of her sacrifice, Artemis turns her into a constellation called "The Huntress."
- * Hemithea – Daughter of King Staphylus of Naxos and granddaughter of Dionysus, she was turned into a god by Apollo alongside her sister Parthenos to escape her father's wrath. She joined the Hunters of Artemis, but later gave up the membership and her immortality with her lover Josephine. The two settled and became protectors of Waystation, where Hemithea became known as "Emmy", and adopted Georgina. She has an interest at plants, with which she quickly befriends Calypso.
- * Josephine – Daughter of Hecate, she was a member of the Hunters until she decided to quit with her lover Hemithea, giving up her immortality in the process. The two became protectors of Waystation and adopted Georgina. She is an expert at mechanics and was previously affiliated with mafia in the early 20th century.
- * Hunter Kowalski – A hunter who attempted to spy on Commodus, she is instead captured and enslaved by him. She is freed by Apollo, Meg, and Leo, and joins them and the others defending the Waystation against Commodus' army.
- Ichthyocentaur – Creatures that have the upper bodies of men, the lower fore-parts of horses, ending in the serpentine tails of fish. Their brows were adorned with a pair of lobster-claw horns. In The Mark of Athena, the demigods encounter the Ichthyocentaurs who save them from Keto and her children. The Icthyocentaurs also run a Camp for Merpeople heroes.
- * Aphros – An Ichthyocentaur who is the half-brother of Chiron. He teaches home economics.
- * Bythos – An Ichthyocentaur who is the half-brother of Chiron. He teaches fighting.
- Kampê – A snake-haired winged centauroid creature who is half-woman, half-dragon with the heads of various animals growing from her human torso. She is a monster who imprisoned the Hundred-Handed Ones and Cyclopes during the First Great War. She is feared by all, and is defeated by Briares in the Battle of the Labyrinth by being crushed by boulders.
- Kerkopes – Two brothers who are the children of Oceanus and Theia. They worked as thieves until they were caught by Hercules and later turned into monkeys by Zeus. In The House of Hades, the Kerkopes have set up shop in Balogna, Italy. When the Argo II docks there, the Kerkopes attacked the ship and robbed it, taking things like an Archimedes Sphere and Piper McLean's dagger Katoptris. Leo Valdez and Jason At the Fountain of Neptune, they incapacitated Jason by trapping him in a net. Leo chases them to their hide-out and defeats them with a home-made flash-bang grenade. He then got their possessions back and agreed not to kill Passalos and Akmon on the condition that they go to America and disrupt the Romans in order to slow down their attack on Camp Half-Blood. Later in a dream, it is shown that they are being very successful in this goal.
- Khromandae - Large, grey-eyed humanoids covered in blonde hair. Khromandae were discovered during Dionysus's invasion of India and communicate via ear splitting shrieks. They were part of Tarquin's, Caligula's, and Commodus's army that attacked Camp Jupiter in The Tyrant’s Tomb.
- Lamia – The daughter of Hecate who was one of the former love interests of Zeus until Hera turned her into a monster after the death of her children. In The Demigod Diaries story titled "Son of Magic", Lamia is revived by Gaia to kill Hecate's son Alabaster Torrington. Alabaster manages to defeat Lamia until Hecate arrives to save both her children. According to Hecate, Lamia won't try attacking Alabaster again, knowing he could use that spell against her.
- Lotus-eaters – A group of humans who were previously encountered by Odysseus. A number of them run the Lotus Hotel and Casino in The Lightning Thief. The hotel is filled with arcade games that makes visitors not want to leave alongside the lotus cookies they serve.
- Maenad – A bunch of Maenads appeared in The Demigod Diaries story "Leo Valdez and the Quest for Buford." They were seen skipping in a mall-shaped clearing in the Camp Half-Blood Forest where a Drakon appeared. They managed to easily rip it apart with their long white talons and their elongated wolf-like fangs.
- Manticore – A monster with the face of a man, the body of a lion, and the tail of a scorpion. In Percy Jackson: Sea of Monsters, a Manticore appeared as a top henchman of Luke Castellan. When it came to the fight at Polyphemus' lair, the Manticore wounded Annabeth before it was killed by Grover Underwood and Clarissa La Rue.
- * Dr. Thorn – A Manticore in human form that appeared in The Titan's Curse. Dr. Thorn is the vice-principal of Westover Hall. He has two eyes of different colours, one blue and one brown. Dr. Thorn's nostrils flare up when he talks. He speaks in a French accent. Dr. Thorn tries to kill people by using thorn-like objects. He is angry that in the ancient days, the Gods forced him to live out in Persia, where he never had any decent challenges, as he would in Ancient Greece. Dr. Thorn is killed by Dionysus.
- Merpeople – A race of sea creatures that are half-human and half-fish. The male merpeople are called Mermen while the female merpeople are called Mermaids. In The Last Olympian, Percy wakes up underwater near Atlantis where he sees various Merpeople in battle armor fighting the forces of Oceanus. There were even some Merpeople making graves for the Merpeople who fell in battle. They serve Poseidon.
- * Bill – A merman that was trained at "Camp Fish-Blood" by Aphros and Bythos.
- Minotaur – The Minotaur is part-man, part bull. The monster of the labyrinth who chased Percy all the way to Camp Half-Blood. Percy defeats the monster atop Half-Blood hill and claims its broken horn as a spoil of war. The Minotaur returns in The Last Olympian as a general for Kronos's army at Williamsburg Bridge and now wearing armor. It was defeated by Percy again. In the film adaptation, the Minotaur's head resembles a Cape Buffalo's head.
- Nymphs – Female, magical beings usually associated with some natural feature. Many different kinds of nymphs are seen in Rick Riordan's novels, including naiads, dryads, and aurae.
- * Aurae – Wind spirits who work at Camp Jupiter as seen in The Son of Neptune.
- ** Mellie – An Aurae who is the wife of Coach Gleeson Hedge and the mother of Chuck Hedge. She is the personal assistant of Aeolus as seen in The Lost Hero. At the end, she works as Piper's dad's assistant Tristan McLean. In The Burning Labyrinth, Mellie appeared at the Aeithales where she greets Apollo and Grover. After hearing of Jason's death, she and Gleeson head to Malibu to help a grieving Piper. When on the airfield, Mellie tells her family that she will be going to the McLean family's home in Oklahoma.
- * – Nymphs that are associated with trees and forests.
- ** Agave - A Dryad that sent Grover to explore the Labyrinth. In The Burning Maze, Agave and Money Maker were found in the burning maze by Grover and those with him. Grover takes them back to Aeithales and Agave is healed while Money Maker dies of her injuries.
- ** Aloe Vera - A caring Dryad who lives in the Aeithales near Palm Springs. In The Burning Maze, Aloe Vera tends to Apollo and Meg when they arrive and even tends to them following an attack by Medea.
- ** Daphne – A dryad whom Apollo fell in love with. Eros, after a conflict with Apollo, shot an arrow that made the latter fall in love with Daphne, yet at the same time shot an arrow that made Daphne hate him. She ran away and, realizing that Apollo would never give up, asked Gaea to transform her into a tree. Apollo still grieves for Daphne's fate, which he considered as one of his two greatest losses, and is frequently haunted by visions of her and other dryads blaming him.
- ** Joshua - A laid-back and nature-loving Dryad who lives in the Aeithales near Palm Springs. According to Apollo, male Dryads like Joshua are rare. In The Burning Labyrinth, Joshua greets Apollo and Meg when they arrive. Meg has a crush on Joshua, and Apollo attempts to give her advice on how to catch his eye, but is ignored and he tells Meg that she is being super obvious.
- ** Juniper – A Dryad who is Grover Underwood's girlfriend. In The Battle of the Labyrinth, she informs Percy that she has seen Luke Castellan using the entrance to the Labyrinth and that she has also seen Quintus/Daedalus using the entrance to the Labyrinth.
- ** Meliae - The Dryads of the ash tree that were born when Kronos castrated Ouranos and his blood fell to Gaea. After Caligula destroyed the greenhouse that Philip McCaffrey was going to plant their seeds, a saguaro cactcus named Hercules hid the seeds. In The Burning Maze, Meg replanted them and they helped to slay Incitatus and the Pandai soldiers with him. Then the Meliai transplanted themselves and put their roots around the pool at the ruins of Aeithales. Their magic worked so well that Aeithales rebuilt itself in a day.
- ** Money Maker - A Dryad that sent Grover to explore the Labyrinth. In The Burning Maze, Money Maker and Agave were found in the burning maze by Grover and those with him. He takes them back to Aeithales. While Agave is healed, Money Maker dies from her burns.
- ** Prickly Pear - A rough and crabby Dryad who lives in the Aeithales near Palm Springs. In The Burning Maze, Prickly Pear greets Apollo and Meg when they arrive and scolds Grover.
- * The Hesperides – The daughters of the Titan Atlas and the sea goddess Pleione who tend to the Garden of the Hesperides which is accessible only during sunset. They are described as looking identical to their estranged sister Zoë Nightshade who was originally a part of them before she became disowned for supporting the gods during the Titan War. They briefly reunite with Zoë and then accompanying Percy and the others in heading to Mount Tamalpais in The Titan's Curse. They warned them that they will not be a match against Atlas and pulled the Ladon card. Zoë retaliates by waking Ladon with a shout, and calling her sisters cowards when they chided her for insanity. As Zoë distracted Ladon to help Percy and Thalia evade it, the oldest of the Hesperides called Zoë a fool and they disappeared.
- * Oreads – A race of mountain nymphs.
- ** Echo – An Oread who loved her voice. Zeus fell in love with Echo causing Hera to curse Echo into repeating everything she says. She did have an encounter with Narcissus at the time when he was admiring his reflection in the water. When Echo evaded the love advances of Pan, she was killed by some panicked shepherds and her fragments were scattered by Gaea. In The Mark of Athena, Leo Valdez and Hazel Levesque encounter Echo on a small island where they were looking for lime and Celestial Bronze that was needed to repair the damaged Argo II. Echo helps Leo get the Celestial Bronze from the lake as Leo makes insults towards Narcissus which Echo repeats. Before Leo leaves, Echo kisses him and briefly becomes more visible; Leo describes her as beautiful, but forgettable
- * Naiads – Nature spirits that inhabit streams and rivers and lakes, or any fresh body of water.
- ** Brooke – Naiad that inhabits the brook in Camp Half-Blood. Gave a warning to Leo, Piper and Jason about her "Crazy Cousins" in The Quest for Buford.
- * Cloud Nymphs – The Cloud Nymphs are mentioned briefly in the series, particularly in The Heroes of Olympus.
- ** Fleecy – A cloud nymph who works at Iris's co-op. She appears in The Son of Neptune. She manages Iris-messaging after Iris begins focusing on her shop. Fleecy is described as young, with frizzy white hair and eyes that change colors from gray to white to black.
- Palikoi – Geyser gods who in times past were worshiped by runaway slaves for protection. Others can make oaths with them. While oaths toward Styx are prolonged and cancerous, a single breach of oath with the Palikoi will result in immediate death.
- * Pete – A Palikoi employed by a marketing company. He is tasked to operate in the Woods of the Camp Half-Blood while collecting surveys on customer service. Apollo makes an oath with Pete to rescue Meg who is kidnapped by the Myrmekes.
- * Paulie – Pete's fellow worker in a marketing company. He is kidnapped by Nero who intends to use his power to break through the Grove of Dodona's walls. Apollo is able to rescue him along with the other abducted demigods.
- Pandai - A long-living war-like tribe from an Indian mountain valley with big ears, eight fingers, eight toes, and white hair covering their body. In The Burning Maze, Caligula uses Pandai and Strix because the Germani were responsible for his mortal death.
- * Amax -
- * Crest - A Pandai who is one of the bodyguards of Caligula. Unlike most of the Pandai, Crest was more interested in music. He later dies buying Apollo time to get away from Medea.
- * Flange - A Pandai who is a messenger for Caligula. Flange was killed by Caligula when he hears that the attack on Camp Jupiter has failed.
- * Peak -
- * Reverb -
- * Timber -
- * Wah-Wah -
- Satyr – Half man, half goat. Most of the Satyrs work at Camp Half-Blood. Their Roman counterpart are the Fauns. Grover Underwood is a satyr.
- * Council of Cloven Elders – A group of Satyrs whose main duty is to abide over the Satyrs' search for Pan. The Council of Cloven Elders reside in the forum within Camp Half-Blood's forest are responsible for determining which Satyrs are worthy of receiving a searchers' license. To achieve a searcher's license, a Satyr must be a successful protector where they must bring a Demigod to Camp Half-Blood alive.
- ** Leneus – A member of the Council of Cloven Elders who hates Grover and thinks he is a liar. He is killed in The Last Olympian and is reincarnated as a laurel. When he dies, Grover takes his place in the Council of Cloven Elders.
- ** Maron – A member of the Council of Cloven Elders. He only appears in book four, when he, Silenus and Leneus try to exile Grover because they think that Pan, the god of the wild, is still alive and Grover is lying about his death. He and the other members of the Council are described as being old and fat satyrs.
- ** Silenus – The leader of the Council of Cloven Elders and is shown to hate Grover calling him an "outcast" and a "liar." He also has suspicions that Grover is a spy.
- * Ichneutae – A satyr who is exclusive to the film Percy Jackson: Sea of Monsters portrayed by Jordan Weller. Ichneutae was present when Clarisse won the obstacle tower. He was chosen by Dionysus to guide her to the Golden Fleece. Clarisse mentioned that he was eaten by Scylla and his last words were "I got this."
- * Lysas – A satyr who was mentioned to have been the chosen one of Pan where he was tasked by the god himself to spread the word that "The great god Pan has died." Even though he refused to believe this, he spread the word to the world in Ephesos. In The Lightning Thief, Grover Underwood mentions that a sailor off the coast of Ephesos heard a mysterious cry saying that Pan has died. It is revealed in The Battle of the Labyrinth that it was a satyr called Lysas.
- * Millard and Herbert – Two satyrs sent by Chiron to find and alert Rachel Dare to visit Camp Half-Blood in The Hidden Oracle. While Rachel is successfully courted in, she states that the satyrs came to her wounded and died soon afterward.
- * Uncle Ferdinand – Grover's uncle who was one of the victims of Medusa in the Garden Gnome Emporium. When Kronos' army was hiding out there in The Last Olympian, his statue form is now missing an arm and has graffiti on it without Medusa to watch over it.
- * Woodrow – A satyr and Camp Half-Blood's music instructor as seen in The Hidden Oracle. He is afraid of Apollo due to the latter's apparent history of flaying a satyr due to his loss in a musical contest which Apollo himself vehemently denies.
- Scythian Dracaenae – A race of humanoid females with twin snake tails in place of legs. They make up a considerable portion of the Titan Lord's forces. In The Sea of Monsters, Percy first encounters them on the Princess Andromeda. In The Titan's Curse, some Scythian Dracaenae attacked Percy's group after he had defeated Atlas. In The Battle of the Labyrinth, Percy fights a Scythian Dracaenae in Antaeus' lair. Percy almost immediately kills it much to Antaeus' disapproval. The Scythian Dracaenae also show up in the actual Battle of the Labyrinth as one of the main types of soldiers. In The Last Olympian, the Scythian Dracaenae are seen taking part in the Titan Army's attack on Manhattan.
- * Queen Sess – The Queen of the Scythian Dracaenae who appears in The Last Olympian. She fought Chiron alongside Kronos and was killed when Chiron fired one of his arrows in between Queen Sess' eyes.
- * Sssssarah - A Scythian Dracaenae. In The Dark Prophecy, she was freed from Commodus by Lester, Leo Valdez, and Calypso.
- Werewolf – A creature that is part man, part wolf. In The Lost Hero, King Lycaon led a pack of werewolves to kill Valdez and McLean. Most of the werewolves were defeated by the Hunters of Artemis.
- * King Lycaon – A king who was turned into a wolf after attempting to test Zeus's omniscience. In The Lost Hero, Lycaon encounters Jason, Leo, and Piper in their search for Aeolus. He and his werewolves attempt to kidnap Jason and kill Leo and Piper at Gaia's command. The Hunters of Artemis thwart the plan, but Lycaon escapes. In The Blood of Olympus, Lycaon confronts Reyna, Nico, and Coach Hedge at Évora to prevent them from delivering the Athena Parthenos to Camp Half-Blood, but he is stabbed by Reyna's silver knife.
- Zombie – A bunch of Zombies were seen as passengers on the Princess Andromeda in The Sea of Monsters. Clarisse used the zombies of Confederate soldiers to operate the CSS Birmingham.
Greco-Roman creatures
- Apollo's Cattle – The sacred cattle herd of Apollo. In The Battle of the Labyrinth, Apollo's Cattle were seen at the Triple G Ranch under Geryon's care since Apollo never has time to take care of them. Apollo was unaware that he was using some of the cattle for meat and feeding them to the monsters that work for Kronos. Although Apollo didn't have any cattle in actual Greek mythology, these cattle are based on the Cattle of Helios.
- Arai – Winged female daemons who inhabit Tartarus. They are similar to the Furies, but their number is not limited to three, and they are under control of Nyx instead of Hades. The spirits carry the grudge of anyone whom their killer have wronged; when Percy kills some of them, they release the grudges of Kampê's death by crushing and Calypso's isolation in Ogygia.
- Arion – A horse born to Neptune and Ceres, making him Percy's half-brother. He appears in The Son of Neptune where Hazel frees him from the Amazons. He is described as having a tan coat with a black mane and tail. He is a free spirit and seems to have a bad temper, being known to curse when his abilities are challenged.
- Aristophanes - A cat that lives in the bookstore in New Rome. In The Tyrant's Tomb," Tarquin tries to interrogate him on where the Sibylline Books are.
- Automaton – Highly developed robots with intricate circuitry that makes them hard to fix. Most are made out of steel, but some like Festus the dragon are made out of celestial bronze or other materials. In the Percy Jackson & the Olympians series, Annabeth discovers that many statues in Manhattan are actually automatons created by Daedalus, an army that could either defend or attack Olympus.
- * Argentum – Reyna's silver Automaton Hound who appears in The Son of Neptune, The Mark of Athena and The House of Hades.
- * Aurum – Reyna's gold Automaton Hound who appears in The Son of Neptune, The Mark of Athena and The House of Hades.
- * Bronze Dragon – An automaton dragon made of bronze created by the campers in Hephaestus' cabin to help defend Camp Half-Blood. He is first shown in "Percy Jackson and the Bronze Dragon" story of The Demigod Files where Percy, Annabeth, and Silena reactivate it to save Charles Beckendorf from the Myrmekes. He was deactivated by Beckendorf with Percy's help afterwards, due to the fact that it was unstable and dangerous. It is fixed by the Hephaestus cabin to protect the camp sometime after this. He is later named "Festus" by Leo Valdez in The Lost Hero when Leo found him hidden in the forest. Although Festus was sliced to bits by the lasers on King Midas' mansion, Festus' head was recovered by Hephaestus who had his cabin build the Argo II with Festus' head as the ship's figurehead. Festus means "happy" in Latin.
- * Celedon – Automatons forged by Hephaestus to serve as Apollo's backup singers. In Percy Jackson and the Singer of Apollo, Percy Jackson had to find the fourth Celedon for Apollo after it left Mount Olympus and fled into Times Square.
- * Colossus of Nero – A gigantic automaton built under Nero's orders in the images of Apollo and himself. Nero uses the statue to invade Camp Half-Blood in The Hidden Oracle. The Colossus proceeds to destroy the Dining Area and Demeter's Cabin before being infected with Apollo's hay fever plague and subsequently decapitated.
- * Mechanical Spiders – A bunch of automaton spiders that were created by Hephaestus.
- * Talos – Talos is a giant automaton. Percy, Thalia, and Bianca fight a prototype of Talos in the Junkyard of the Gods. Apparently, he has a manhole at the base of his foot for 'servicing'. Bianca went in to mess up his circuit so they could defeat him. He fell on some power lines thus electrocuting Bianca.
- Basilisk – Fire-breathing snakes with colorful spikes and poisonous bites. In The Son of Neptune, they attacked Camp Jupiter, but Frank shapeshifts into a mongoose and scares them off.
- Buford – A walking table that Leo Valdez saved from a supply closet and prefers to be polished by Lemon Pledge instead of Windex. He assists Leo Valdez in constructing the Argo II in Bunker 9. Eventually, Leo programs a talking mini-hologram of Gleeson Hedge onto Buford.
- Carthaginian Serpent - A 120 ft. serpent. In The Dark Prophecy, Apollo, Meg, and Leo face this monster while making their way to Commodus' lair. Apollo tricked it into crashing into a nearby condemned condiminium.
- Centicore – Deadly antelope-like creatures who were tasked to guard the Cave of Trophonius. Due to their endangered status, Apollo goes to great lengths not to kill them as he soaks himself in the waters of Lethe and Mnemosyne.
- Cerberus – The three-headed dog who guards the entrance to the Underworld. In The Lightning Thief, he befriends Annabeth. He also appears in The Last Olympian when he is playing with Mrs. O'Leary. Cereberus is the son of Echidna and Typhon.
- Charybdis – One of the two monsters who live on either side of a narrow channel of water. She takes the form of a giant mouth that swallows and releases water, creating whirlpools. she is described by Percy as an "orthodontist's nightmare".
- Chimera – A three-headed beast that is part lion, part goat, and has a snake-headed tail. It is first seen in the form of a Chihuahua. It confronted Percy atop the St. Louis Arch alongside its mother, Echidna. Overwhelmed by the creature and poisoned by its snake head, Percy was forced to jump into the water far below to escape it. It disappeared after Percy dove into the water.
- Clazmonian Sow – A flying pig that appeared directly after Hyperion was defeated. Percy defeats it with the help of Blackjack, a statue of Hermes, and the New York Public Library's two stone lion statues.
- Colchis Bull – Fire-breathing bronze bulls created by Hephaestus with horns of silver and rubies for eyes. In The Sea of Monsters, some of these bulls attack Camp Half-Blood and are defeated by Tyson. They were later used to make the tracks for the Chariot Race.
- Dragons – Large reptilian creatures that sometimes have wings. They are used for guarding things and are younger than Drakons.
- * Draco Aionius – Some of these monsters attacked Camp Half-Blood while Percy Jackson was on his adventures in The Sea of Monsters.
- * Ladon – A giant dragon who is one of the offspring of Echidna. It defends the Hesperides' apple tree. Ladon poisons Zoë Nightshade in The Titan's Curse.
- * Peleus – A dragon that is now guarding the Golden Fleece which hangs on the tree that Thalia was previously within. He is possibly named after Peleus: Father of Achilles.
- * Python – A giant Earth Dragon who was an old enemy of Apollo. In The Blood of Olympus, Python was revived by Gaea during the Second Gigantomachy and it was mentioned that Python reclaiming Delphi was one of Apollo's many failures. In The Hidden Oracle, Apollo and Meg McCaffrey are in the Labyrinth where they overhear Python talking to Nero about the plans to control all the Oracles.
- * Sun Dragons - The Sun Dragons are a type of Dragon that are associated with Helios.
- ** Phil and Don - Sun dragons that Helios gave his granddaughter Medea to pull her golden chariot. In The Lost Hero, Medea keeps Phil and Don in large sundial compartments at her department store. She releases them to attack Jason Grace, Piper McLean, and Leo Valdez. Phil and Don were defeated by Festus. In The Burning Maze, Phil and Don pull Medea's golden chariot when she challenges Meg to a charmspeak battle. Both of them are beheaded by Meg McCaffrey where their deaths released an intense blast of heat.
- Drakons – Giant serpent-like creatures that are several millennia older than dragons. They come in three different types: Aethiopian, Lydian, and Maeonian. In The Demigod Diaries story titled "Leo Valdez and the Quest for Buford", an unidentified Drakon appeared in the Camp Half-Blood Forest until it was ripped apart by the Maenads.
- * Aethiopian Drakon – A Drakon with terrifying green eyes that originated from Africa. One was being raised by Luke in The Sea of Monsters. When one of the Bear Twins seemed reluctant to do his bidding, Luke threatened to feed him to the Drakon. In The Battle of the Labyrinth, an Aethiopian Drakon was seen in the cargo bay of the Princess Andromeda.
- * Lydian Drakon – The oldest and fiercest of the Drakons that once attacked the village of Lydia. It is a 200 ft. long Drakon with a paralyzing stare in sheer terror and armor-corroding acidic venom. In The Last Olympian, Kronos unleashed it upon Manhattan where it killed many half-bloods before being killed by Clarisse La Rue.
- * Maeonian Drakon – A green and yellow Drakon that once attacked Maenoia, Turkey. In The House of Hades, the Maeonian Drakon resides in the swamps of Tartarus. It attacked Percy, Annabeth, and Bob the Titan and was killed by Damasen. Damasen's curse was to slay the Maeonian Drakon every day.
- Eidolons – A race of spirits that can possess demigods. In The Mark of Athena, the Eidolons work for Gaea.
- Elephant - The elephants are large herbivores native to Africa and the southern parts of Asia. Any elephant that is bredfor war is called a war elephant.
- * Hannibal - A war elephant that is owned by Camp Jupiter and is often cared for by Bobby.
- * Livia - A war elephant that is owned by Commodus. In "The Dark Prophecy," Livia was present at the rehearsal of Commodus' naming ceremony until she was rescued by Apollo and Thalia. In "The Tyrant's Tomb," Apollo makes a claim that she and Hannibal would get along.
- Erymanthian Boar – A giant boar and servant of Pan who appears in The Titan's Curse. Percy, Thalia, Zoë, Grover, and Bianca first encounter it in Cloudcroft, New Mexico where Grover realizes its potential as a form of rapid transportation.
- Fire-Breathing Horse – A race of horses bred at the Triple G Ranch for war purposes. Some are shown to pull Ares' war chariot. In The Dark Prophecy, some Fire-Breathing Horses are owned by Commodus.
- Flesh-Eating Horse – A group of female horses bred at the Triple G Ranch. Some of them tried to eat Percy while he was cleaning the stables.
- Flesh-Eating Sheep – A race of carnivorous sheep owned by Polyphemus. They help to guard the Golden Fleece. Described as being a big as a hippopotamus and attacking like piranhas.
- Giant Badger – A giant badger. In The Last Olympian, it was mentioned that Gleeson Hedge tried to fend off the Giant Badgers and tried to summon Pan to help him to do that.
- Giant Crab – A giant crab that might be Cancer. Percy fought it in the Princess Andromeda during his mission with Charlie. He defeated it by stabbing the soft tissue on its belly.
- Giant Eagle – A giant-size eagle that appears throughout The Heroes of Olympus series. The Giant Eagles are mainly used by the Romans for transporting and protecting Roman demigods.
- Giant Scorpion – A giant-sized scorpion. Daedalus ordered some Giant Scorpions from the Triple G Ranch and kept them in their boxes in the Sword Fighting Arena. He eventually let them out in the camp's forest for a game.
- Giant Sea Turtle – A large sea turtle who accompanied Sciron into attacking the Argo II as seen in The House of Hades.
- Giant Snake – A large snake. It attacked Tyson and Grover when they were in the Labyrinth as seen in The Battle of the Labyrinth.
- Giant Squid – A giant squid that might be the Kraken. It was among the sea monsters in Oceanus' army.
- Gryphon – A creature that is part eagle, part lion. They are known to collect golds for their nests and even lay golden eggs. The Gryphons appear in The Son of Neptune where they are seen in Alcyoneus' camp. They are not to be confused with the griffins of The Kane Chronicles.
- * Abelard - A pet Gryphon to Britomartis who appeared in The Dark Prophecy.
- * Heloise - A pet Gryphon to Britomartis who appeared in The Dark Prophecy. She lays an egg while in Commodus' captivity and is later killed during the battle at Waystation.
- Hellhound – The Hellhounds are a main part of Luke's army and monsters in general. They are described as very large black dogs that have fire glowing in their eyes. They were also mentioned to reside in the Fields of Punishment. Daedalus owns a hound named Mrs. O'Leary, who, unlike her relatives, is loving and loyal. In The Last Olympian, a bunch of Hellhounds are seen in Kronos' army where they snuck behind the demigod lines.
- * Mrs. O'Leary – Mrs. O'Leary is the only friendly hellhound to ever exist. Quintus was her original owner, but, after asking Nico di Angelo to kill him, Percy becomes the hellhound's owner. While Percy is in the "mortal world", Charles Beckendorf takes care of her at Camp Half-Blood. She rescues Percy while in the Labyrinth.
- Hippalectryon – An endangered animal that is part chicken, part horse. In Battle of the Labyrinth, they are seen at the Triple G Ranch.
- Hippocampus – Creatures that are horses from the waist up with a fish tail from the waist down. One is said to take a liking to Tyson, and he named it Rainbow. They are also called "fish ponies" by Tyson.
- * Rainbow – A Hippocamus who befriends Tyson in The Sea of Monsters. Loves to give Tyson rides all over the sea.
- Incitatus - A talking white horse that wears golden horseshoes and is owned by Caligula. In The Burning Maze, Incitatus brings Apollo and Meg to Caligula. He later assists Caligula in fighting Jason and Tempest which ends in Jason's death. During the fight at the old Los Angeles Zoo, Incitatus and the Pandai that are with him are killed by the Meliai.
- Hydra – A serpentine monster with nine heads. Every time a head is chopped off, two new heads grow back. This monster appears in The Sea of Monsters where its life force is linked to the Monster Doughnut Shop, as another one pops up every time the Hydra regrows a head. It was destroyed by the cannons of the CSS Birmingham. In The Mark of Athena, Percy fights a Hydra when he, Jason, and Piper are on a mission to rescue Nico from Ephialtes and Otis. In ' film, the creature takes the form of five janitors in the Parthenon replica in Tennessee and refers himself as "We." The Hydra is ultimately defeated by the use of Medusa's head.
- Karpoi – Grain spirits who are the size of toddlers. While many of them are malevolent thanks to their service to Gaea, children of Demeter are apparently also capable of summoning karpoi.
- * Peaches – A friendly Karpoi that resembles a pudgy human toddler with green eyes and green hair. He is controlled by Meg McCaffrey.
- Keres – Spirits of famine and disease who feed on violent deaths. They reside in the Underworld and support the Titans but do not assist them in The Last Olympian. In The Demigod Files story "Percy Jackson and the Sword of Hades," some of them attacked Percy, Thalia, and Nico. One of them poisoned Percy, yet "Bob the Titan" managed to heal him.
- Katobleps – A race of cow monsters that appear in The House of Hades.
- Ketos – Chiron mentions this giant sea monster in The Titan's Curse.
- Khromandae - A race of monsters with shaggy blonde fur, gray eyes, sharp teeth, and speak in high-pitched shrieks. Dionysus once used them in his drunken invasion on India. In "The Tyrant's Tomb," the Kromandae were used during the Battle of San Francisco Bay where they are taken out by Apollo and Meg.
- Lemures – A race of angry ghosts who are seen on multiple times in The House of Hades.
- Leucrotae - Creatures that had the body of a red-furred lion and the hooves and tail of a horse and can't be harmed by metal weapons. In The Demigod Diaries story "The Diary of Luke Castellan," Luke and Thalia were trapped in Halcyon Green's mansion and encountered by two Leucrotae that speak with a man's voice. The two of them discovered that the Leucrotae are linked to Halcyon's thoughts. When Thalia uses fire on the Leucrotae, Halcyon sacrifices his life by luring the Leucrotae away so that Luke and Thalia can escape.
- Leviathan – These are mentioned by Poseidon in The Last Olympian as giant sea creatures that are neutral in the war between Poseidon and Oceanus.
- Lupa – The wolf that raised Romulus and Remus. She guides the children of Roman gods to Camp Jupiter after they are left for her at the Wolf House where she trains them to become Roman soldiers upon finding the worthy ones. She is the Roman counterpart of Chiron who does a similar job for the Greek demigods, only she is more militaristic.
- Makhai – The spirits of battle and combat. In The Blood of Olympus, Asclepius used the Makhai and the Pylosian Mint to formulate a physician's cure.
- Mania – Ghosts that personify insanity, madness and crazed frenzy. In The Blood of Olympus, Beryl Grace and Julian Ramírez-Arellano are among the Mania.
- Myrmekes – Giant ant-like creatures who like shiny things like gold. In The Demigod Files story "Percy Jackson and the Bronze Dragon," some Myrmekes trapped Charles Beckendorf in their nest. In The Hidden Oracle, Apollo and Meg come across a trio of Myrmekes who kidnap Meg, forcing Apollo to infiltrate their nest and rescue her. Later, Apollo successfully persuades the mother ant "Mama" to help him and other demigods return to Camp Half-Blood.
- Nemean Lion – A lion that is one of the children of Echidna and Typhon. It has a hard skin in which no weapon can penetrate. Luke and Atlas sent the Nemean Lion to the National Air and Space Museum to stop the group of questing Hunters and Demigods. It battled with Percy Jackson, but was hard to defeat because of its bulletproof and sword-proof pelt. Percy eventually defeated it by throwing astronaut food into its mouth thus exposing its one unprotected surface, its mouth.
- Nosoi – The spirits of illness, plague, and disease that were originally locked up in Pandora's Box. In The Hidden Oracle, a bunch of Nosoi attack Apollo and Meg McCaffrey until they are fended off by them and the Karpoi Peaches.
- Ophiotaurus – A half-cow/half-snake monster. It was nicknamed Bessie by Percy Jackson who initially assumed it was female, although Grover later informed him that it was a male. Percy saved it from a trawler's net after being fetched by the Hippocampi. Bessie was supposedly the creature that Artemis was hunting because it could destroy Olympus. She/He appears in The Titan's Curse and The Last Olympian.
- Orthrus – A two-headed dog owned by Geryon and brother to Cerberus.
- Pegasus – Winged horses that are named after the original mount of Bellerophon that was born from the blood of Medusa.
- * Blackjack – A pure black Pegasus and Percy's loyal friend. He is first introduced in the second book The Sea of Monsters on the Princess Andromeda where Percy rescued him from Kronos's minions. Ever since then, Blackjack has felt like he has to pay Percy back for saving him and he does whatever Percy asks calling him "boss." He is seen in The Blood of Olympus delivering the Athena Parthenos to Camp Half-Blood.
- * Guido – A light gray and white Pegasus who is friends with Blackjack. In The Last Olympian, Guido and Porkpie aided Percy and Blackjack in the Battle of Manhattan. Guido later adopts Reyna for his human after the Giant War.
- * Porkpie – A light gray and white Pegasus who is friends with Blackjack. In The Last Olympian, Guido and Porkpie aided Percy and Blackjack in the Battle of Manhattan.
- * Scipio – Reyna's Pegasus who appears in The Son of Neptune. His nickname is "Skippy" because he's the color of peanut butter. He died at the end of The House of Hades because of a gryphon strike.
- Pit Scorpion – A deadly type of scorpion that appears in The Lightning Thief. When Luke brings Percy into the woods and reveals his allegiance to Kronos, he summoned a Pit Scorpion to attack Percy. He tells Percy he should not go for his sword, as the pit scorpion can kill in sixty seconds, and can jump up to fifteen feet. When Luke disappears, Percy manages to kill it even though it managed to sting him. Wood nymphs help Percy recover from its poison.
- Scylla – One of the two monsters who live on either side of a narrow channel of water in The Sea of Monsters. Should a ship sail too close to her, she uses her six heads to pluck off crew members on deck and devour them. According to Clarisse, Scylla would just pick up the whole boat and crushed the boat if the crew hid below deck. In the film Percy Jackson: Sea of Monsters, Scylla was mentioned by Clarisse to have eaten Ichneutae.
- Sea Serpent – A large serpent that lives in the sea. Deimos is seen riding one in The Demigod Files story "The Stolen Chariot." In The Last Olympian, a sea serpent was seen amongst the sea monsters in Oceanus' army.
- * Carthaginian Serpent – A giant serpent with a deadly venom who guards the entrance of Commodus' lair in Indianapolis.
- Sirens – Dangerous bird women whose sweet songs lead many sailors to their deaths on the jagged rocks. In The Sea of Monsters, they almost killed Annabeth.
- Skeleton – Skeletons are the undead troops that make up Hades' Undead Army. In The Lightning Thief, Hades has skeletons in army uniforms guarding his palace. In The Battle of the Labyrinth, Nico manages to employ them as part of a ritual that will enable him to call the spirit of his sister to speak with her. In The Last Olympian, Nico and Hades manage to bring a troop of skeletons to help fight the Titans. They are later seen constructing a cabin at Camp Half-Blood which is dedicated to Hades. In the "House of Hades," they are on the demigods side and help them in the Hades's temple in Epirus.
- Skolopendra – A sea monster that is 200 ft. long. It looks like a cross between a giant shrimp and a cockroach with a pink chitinous shell, a flat crayfish tail and millipede-type legs. Its face is a slimpy pink like an enormous catfish with two glassy dead eyes and a gaping toothless maw. It has a beard which has numerous tentacles sprouting from each nostril. In The Mark of Athena, Ceto sent Skolopendra after the demigods after their escape from Phorcys' aquarium. It attacked the Argo II when Leo forgot to turn the monster-detection system on. Percy describes Skolopendra as "shrimpzilla." Skolopendra withdraws into the ocean when Leo Valdez and Hazel Levesque throw test tubes filled with Greek Fire into its mouth.
- Spartus – A troop of skeletons armed with weapons. They are usually summoned by planting dragon teeth in the ground and watering them with blood. In The Titan's Curse, some Spartoi ambushed Percy, Thalia, Zoe, Grover and Bianca in New Mexico. Due to her being a child of Hades, Bianca managed to destroy them. In The Son of Neptune, Frank is given a spear with the tip of a dragon's tooth that when planted with raise one of the Spartoi, he uses this to defeat the basilisks outside of the R.O.F.L. headquarters, to kill some of the laistrygonians surrounding his grandmothers house then using his final charge to protect the mortals on a train from attacking Griffins.
- * Gray – A Spartus that can be summoned by Frank Zhang.
- Sphinx – A monster with the head of a woman and the body of a lion. Percy Jackson and his friends encountered the Sphinx while navigating the labyrinth. Rather than tell riddles, the Sphinx asked historical questions which Annabeth refused to answer as an insult to her intelligence. They are not to be confused with the Sphinx from The Kane Chronicles.
- Strix - A race of owl-like creatures that eat the flesh and blood of humans. They also curse the mortals who kill them. Anyone scratched by the talons of the Strix will be paralyzed. In The Burning Maze, Apollo's Lester Papadopoulous form was chased by a flock of Strix. After one Strix gets through the tomato bomb and scratches Lester on the cheek, Grover was able to reason with it as the Strix states that it was sent by Emperor Caligula to kill them. Under the advice of the Arrow of Dardona, Meg and Grover grew strawberries to distract the flock of Strix so that they can get away. Other Strix appeared on the Julia Drusilla Yachts where Caligula uses them as surveillance. Caligula replaced the Germani with Strix and Pandai because the Germani are responsible for his mortal death.
- Stymphalian Birds – A flock of birds once attacked Camp Half-Blood in The Sea of Monsters. Percy and Annabeth used Chiron's music to scare them so Apollo's cabin could shoot them down. A flock of Stymphalian Birds attack the Argo 2 in The House of Hades. In The Demigod Files, Phobos summons them to fight Clarisse after he steals Ares' war chariot.
- Telekhine – Dog-faced sea demons that reforged Kronos's blade in the fourth book. In The Mark of Athena, some Telekhines are seen in a water tank at the Georgia Aquarium.
- Trojan Sea Monster – A sea monster that rampaged the coasts of Troy until it was slain by Heracles. It is also known as the Keto Trois. In The Lost Hero, Jason Grace claims to have slew this monster while fighting Porphyrion of the Gigantes.
- Typhon – A very powerful monster. He sired many monsters by Echidna. He lives and sleeps inside Mount Saint Helens. Percy is such a powerful demigod that he almost wakes Typhon during his visit there. In The Last Olympian, Typhon awakes and moves across America destroying everything in his path. As he is concealed in mist, Typhoon's appearance is not described and appears as a freak storm. The gods of Olympus try to stop him, but he is too powerful. In the end, Poseidon and his army help defeat him where Poseidon opened up a tunnel that sends Typhon into Tartarus. Once Typhon was defeated, a wave of anemoi thuellai were born.
- Unicorn – A horse with one horn. A herd of Unicorns are used as steeds for the campers of Camp Jupiter. A red-tinted Lares with the head of a wolf guards them.
- * Buster - A unicorn that lives in Camp Jupiter. In "The Tyrant's Tomb," Meg and Pranjai use his horn shavings to tend to the scrath on Apollo's stomach. He later joins the other unicorns in fighting the invading zombies during the second wave of Caligula's Assault on Camp Jupiter.
- * Horatio - A unicorn that lives in Camp Jupiter. In "The Tyrant's Tomb," Horatio is among the unicorns that fight Tarquin's army during the Battle of San Francisco Bay.
- * Muffin - A unicorn that lives in Camp Jupiter. In "The Tyrant's Tomb," Muffin is among the unicorns that fight Tarquin's army during the Battle of San Francisco Bay.
- * Shirley - A unicorn that lives in Camp Jupiter. In "The Tyrant's Tomb," Shirley is among the unicorns that fight Tarquin's army during the Battle of San Francisco Bay.
- * Whagadoodle - A unicorn that lives in Camp Jupiter. In "The Tyrant's Tomb," Whagadoodle is among the unicorns that fight Tarquin's army during the Battle of San Francisco Bay.
- Venti – A race of storm spirits that were born when Poseidon opened a tunnel that sent Typhon into Tartarus. Depending on how chaotic they are, Venti can appear as either smokey men with angel-like wings or smokey horses. In The Lost Hero, Aeolus sent the Venti to prevent Jason, Piper, Leo, and the Hunters of Artemis from rescuing Hera. Their Greek counterparts are anemoi thuellai.
- * Dylan – A ventus that was among the Venti that attacked Jason Grace, Piper McLean, and Leo Valdez as seen in The Lost Hero.
- * Tempest' – A ventus in smokey horse form that appears in The Lost Hero. Jason tames Tempest so that it can help him fight Porphyrion.