The Demon was created by Jack Kirby. The titular character, named Etrigan, is a demon from Hell who, despite his violent tendencies, usually finds himself allied to the forces of good, mainly because of the alliance between the heroic characters of the DC Universe and Jason Blood, a human to whom Etrigan is bound.
Jack Kirby created the Demon in 1972 when his Fourth World titles were cancelled. According to Mark Evanier, Kirby had no interest in horror comics, but created Etrigan in response to a demand from DC for a horror character. Kirby was annoyed that the first issue sold so well that DC required him to remain on it and abandon the Fourth World titles before he was done with them. Etrigan was inspired by a comic strip of Prince Valiant in which the titular character dressed as a demon. Kirby gave his creation the same appearance as Valiant’s mask.