At the 2008 Screenwriting Expo
His first job was working as an editor for Warner Bros.' animation department. Working at the Skywalker and Big Rock Ranch facilities with George Lucas he co-wrote the animated series Star Wars: The Clone Wars. He served as head writer for season one, penning several episodes. He is also the author of several Star Wars comic books. He is co-creator of the first Bionicle trilogy. Gilroy has since written for numerous animated series, such as Taz-Mania, Batman: The Animated Series, Justice League, G.I. Joe: Renegade and several Disney television series and the direct-to-video title Atlantis: Milo's Return. Along with Ronnie del Carmen, Gilroy co-wrote the four-issue Joker/Mask comic book which was collected by Dark Horse/DC in 2001. He also wrote the film Mass Effect: Paragon Lost.
As of 2016, Henry Gilroy is the co-executive producer of the Star Wars Rebels TV series.