He first appeared in The Last Hero by Terry Pratchett, heavily illustrated by Paul Kidby. At that time he prohibited the eating of chocolate, ginger, mushrooms, and garlic by his followers.
His existence is the basis for Terry Pratchett's latest novel Monstrous Regiment. Among his ever-growing list of Abominations are chocolate, cats, the color Blue, Dwarfs, Oysters, babies, cheese, the smell of beets, and ears.
He is thought to be either insane or dead.