Prior to his association with Disney, Van Horn drew and wrote a black and white comic book called Nervous Rex for Blackthorne Publishing. Focusing on the misadventures of a small, non-violent tyrannosaurus, the series ran for ten issues, from 1985 to 1987. Afterwards, also for Blackthorne, he drew and wrote a short-lived superhero parody comic called "Possibleman," which ran for two issues. William's son Noel Van Horn is also a Disney comics artist, focusing on Mickey Mouse-stories. William Van Horn created the following characters for the Duck universe: