The Cerberus is a monster of Greek mythology, which fought Hercules. The Marvel adaptation was created in 1966 by Stan Lee and Jack Kirby. Making its first appearance in issue #130 of the 1st volume of the Thor comic book series.
The Cerberus is a descendant of Set, an Old One. It was sired by Set's granddaughter Echidna who mated with Typhon, one of the Titans. A multi-headed large dog with a scorpion tail which guards the gates of Tartarus. It can shapeshift into a larger dog or into a minotaur-like humanoid. When in humanoid form it's able to transmute objects into weapons, carries a warhammer, and fires blasts from his helmet.