A Demon is a relatively big, pink, bulky, muscular, vaguely humanoid monster with sharp teeth, two horns on its big head, backwards knees and three claws on each foot. It will chomp you like a wild animal, and runs at 10 mph. They are called "pinkies" by various Doom fans, as well as Coulden, but he prefers to call them as demons.
Demons also appear in Erika Adventures: Makron's Revenge as villains. Pointed ears serve as placeholders for horns.