Cerberus is Hades' three-headed dog guard of the Underworld.
Cerberus first appears when Hades is riding down the River Styx and is fed a massive steak. Later, Hercules tames the beast and uses him to get to Hades inner sanctum, though this is only a temporary turn driven by fear.
Cerberus appears as a rambunctious puppy Hades has difficulties in controlling.
Role in the Series
Cerberus reprises his role in the movie, but also now has a larger role due to the fact that we actually get to see Cerberus as one of the monsters in a battle against Sora and his friends unlike what happend in the real film. also unlike the real film, cause of him being defeated by Boy Sora, Donald and Goofy, Seadramon replaces him for the break in to the under world.