"Smilin' Jack" developed an extremely colorful and imaginative band of supporting characters through its lengthy run, including the handsome Downwind Jaxon; Fat Stuff, a humorous Hawaiian character; hillbilly mechanic Rufus Jimpson; glamorous air hostess Dixie Lee; and eventually Jack Jr., plus various romantic interests, referred to by Mosley as "de-icers".Villains included The Claw, Toemain the Terrible, The Head and his sister, The Mongoose.