Cerberus

Cerberus is Hades' three-headed dog guard of the Underworld.

HerculesEdit
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.

Hercules: the Animated SeriesEdit
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 Hercules tame Cerberus in a boss battle alongside Sora and Spongebob before they get to take down Hades once and for all.