Mark McClellan was a writer who wrote on two episodes of the animated version of Fraggle Rock, with John Semper and Cynthia Friedlob: "Homebody Matt" (story) and "The Funniest Joke in the Universe" (teleplay).

McLellan wrote for The Smurfs and the toy tie-in series Moon Dreamers. He wrote for comic books, including the short-lived Nintendo line (Captain N, Super Mario Bros., Gameboy) and Archie Comics. He was the main writer for the adult Penthouse Comix.