Agrelot was born in Santurce, Puerto Rico of Italian descent. He was the third of four children by Felipe Agrelot and Ana Luisa Vilá; his sister Ana Luisa, a teacher, later became a part-time comedic actress as well. He started working on radio stations when he was 14. At that time, he was employed by radio entrepreneur Tomás Muñiz, then the general manager of WIAC-AM and the father of later producer and actor Tommy Muñiz. During this period Agrelot developed his first comedic character, Torito Fuertes, a mischievous eight-year-old for a family comedy show sponsored by Borden, Inc. and its evaporated milk. The character later took a life of his own on a radio show first named El Profesor Colgate and later called El Colegiode la Alegría. This program featured Tommy Muñiz as the schoolteacher of a rather dysfunctional classroom. Apart from appearances in numerous commercials, Agrelot's credits in Puerto Rican television included:
"Don Pulula", a mild mannered evangelical pastor with a proclivity for mild double entendres,
"Mario Trauma", a crazed mental patient who constantly screamed in falsetto and was in reality saner than the people around him,
"Pasión", an old maid desperately looking for male company,
"Serafín Sin Fin y Sin Meta", an effeminate man with a heart-shaped birthmark in his cheek
"Soldado Manteca", an inept Beetle Bailey-like character who was part of the United States Army
"Cerebrito Ligón", a man who claimed to be a peeping Tom but wouldn't dare to peep. A famous episode had a young Alida Arizmendi, later a Puerto Rican legislator, confronting him while he tried to sneak into an all-female gym;
"Speedy González", an extremely fast gibberish-talking handyman, who would always charge US$10.00 for his services. This character was a favorite of Benicio del Toro's.
"Don Remigio Rodríguez y Rodriguez", an almost catatonic, extremely frank businessman who had a proclivity for face gestures and sticking out his tongue. He had a standing feud with Joaquín, the Spanish-born store owner across the street, to whom he constantly insulted Don Rodríguez later starred in Sunshine Logroño's film, "Chona, La Puerca Asesina"
El Juez, a character modeled after Pigmeat Markham and Sammy Davis, Jr.'s "Here Come Da Judge" character who had a huge mallet and would use it against a defendant's head if necessary during trials
Don Segismundo, the mayor of Trujillo Bajo, a fictional municipality in Puerto Rico
"Pancho Matanzas", a Cuban immigrant that, as many did at the time, would sell anything to support himself and his family.
"Juan Macana", a not-very-bright police officer, PRPD badge number 13,378 who popularized in Puerto Rico a phrase Agrelot constantly heard in Mexico during one of his tours: "Sí, ¿cómo no?"
Agrelot would also parody famous characters from film and cinema in his comedy program, "Ja Ja, Ji Ji, Jo Jo Con Agrelot". His most famous parody was that of Marlon Brando as Vito Corleone in The Godfathermovie trilogy. Agrelot appeared as Padre Ambrosio, a priest, in Jacobo Morales's Dios Los Cria II. He also played a serious dramatic role in a television miniseries, Nadie lo va a saber, in 1991.
