Stewart scripted for animation ("Kissyfur") and created the short film, "The Year the Universe Lost the Pennant" (1961). He edited and designed magazines ("Castle of Frankenstein", "Flashback"), wrote comics for several publishers (Byron Preiss, Marvel, Warren, Charlton, "Heavy Metal") and contributed to Jay Lynch's "Roxy Funnies" (1972). He collaborated with Larry Hama on pages for "Gothic Blimp Works", the underground comix tabloid published by the "East Village Other", and succeeded Vaughn Bodé as editor, later teaming with Kim Deitch as co-editor of the tabloid.