His first job was on the short-lived animated sitcomMission Hill. He has written for several other series including: Justice League, The Simpsons, Hope & Faith, Boston Legal, Lipstick Jungle, Eli Stone, The Vampire Diaries, , My Family, and Warehouse 13. In November 2015, Kreisberg signed a multi-year deal with Warner Bros. Television, through which he would continue to develop new projects as well as remain the sole showrunner of The Flash, co-showrunner of Supergirl, and executive producer on Arrow and Legends of Tomorrow. In November 2017, his position with Warner Bros. was terminated.
''Fringe''
In 2009, he joined the FOX science-fiction/horror series Fringe as a co-executive producer and writer. At the end of season one, Kreisberg left the show. He co-wrote the following episodes:
"Midnight"
"Unearthed"
''Booster Gold''
In 2011, Kreisberg was hired to write a pilot based on DC Comics hero Booster Gold, for Syfy. The script has gone through many iterations and is said to still be in consideration at the network.
Arrowverse
In 2011, Kreisberg, Marc Guggenheim, and Greg Berlanti began developing Arrow, a re-imagining of the DC Comics comic book character Green Arrow for The CW. In January 2012, The CW picked the project up to pilot. On January 31, 2012, actor Stephen Amell was cast in the title role of Oliver Queen/Arrow. On May 11, 2012, The CW order Arrow to series. It premiered on October 10, 2012. In July 2013, it was announced that Kreisberg, fellow Arrow co-creator Berlanti and DC Comics CCO Geoff Johns would be introducing Barry Allen during the show's second season, with the twentieth episode serving as a backdoor pilot. Actor Grant Gustin was cast and first appeared in the eighth episode of the second season, "The Scientist". The CW producers were pleased with the handling of the character, and greenlit a pilot episode, foregoing the backdoor version. In May 2014, The Flash was officially ordered to series. It premiered October 7, 2014. On February 26, 2015, it was announced that Kreisberg, along with Guggenheim and Berlanti, would write/executive produce a spin-off series featuring Caity Lotz, Victor Garber, Brandon Routh and Wentworth Miller as White Canary, Martin Stein, The Atom and Captain Cold respectively, for a potential 2016 premiere. The series, titled Legends of Tomorrow premiered on January 21, 2016.
Comics
Kreisberg has written for the comic book seriesGreen Arrow and Black Canary and Batman Confidential. In 2008, Arcana Comics began publishing Helen Killer, a comic book by Kreisberg with art by Matthew Rice. In it, a college-aged Helen Keller is given a device which allows her to see and hear and which increases her physical abilities, at which point she is hired to protect the President of the United States. It was announced in July 2014, that Kreisberg and Arrow executive story editor Ben Sokolowski would be taking over the Green Arrow title in October of that year, beginning with issue #35.
Allegations of sexual harassment
On November 10, 2017, Kreisberg was suspended from his role as showrunner on The Flash, Arrow, Legends of Tomorrow, and Supergirl, after fifteen women and four men accused him of sexual harassment. On November 29, 2017, he was fired from all Warner Bros. Television's projects.
