Cerberus is a supporting antagonist in the Kingdom Hearts Unlimited Saga, mostly appearing in the Mt. Olympus campaigns as a recurring giant boss fought in the Coliseum Tournaments.
He is Hades' three-headed guard dog whose main duty is to guard the entrance to the Underworld. He is also one of Queen Echidna's monstrous brood of children, bred to eventually succeed the Ancient Ones as the bloodthirsty masters of the universe.
Cerberus is a massive, three-headed dog with black fur and short, cropped ears. His heads are identical to each other, each sporting the same enormous mouths, pink tongues, and long, sharp teeth. All three heads also feature glowing red eyes. Cerberus's legs are rather short, and each ends in a paw with three grey claws. He also has a thin tail and seems to be quite muscular.
Cerberus has an angry and/or feisty personality, but will obey his master, Hades, whenever he is called into battle. However, he will retaliate if Hades beats him too much.
Cerberus is an Olympian Monster of Tartarus alignment, which allows him to use dark magic in battle. For instance, he can vomit a black flowing pool of dark energy into the ground from all three of his mouths, which will then spread to the arena and erupt into miniature geysers. He can also spit out huge molten fireballs from any mouth to pick off fleeing targets. His leg and chest muscles are well ripped, providing him great strength in leaping, running, or stomping on the ground. His teeth are razor sharp, and can brutally tear a victim in half with one bite.