In the first years of his career as a Disney Comics artist William often worked with John Lustig on the stories. At one time in 1994 He helped Carl Barks do a story titled Horsing around with History which was released in Uncle Scrooge Adventures #33. Van Horn still does comic books for foreign countries.
William's son Noel Van Horn was also a Disney Comics Artist. Here is a list of characters William Van Horn created for the Scrooge McDuck Universe:
Baron Itzy Bitzy - a whistling flea that Scrooge has. Rumpus McFowl - Scrooge's half brother who is also his cousin. Woimly Filcher - an enemy of Donald Duck and his nephews.