Cerberus

A carving of Cerberus, with the usual three heads.

Cerberus is a monster from Greek and Roman mythology. He takes the form of a ferocious, many-headed dog; the number of heads varies between accounts but is usually three. Cerberus guarded the entrance to Hades, the realm of the dead. The final labor of Hercules was to bring Cerberus to the surface.

Other mythologies also feature creatures similar to Cerberus. For example, in Norse mythology, Hell is guarded by a four-eyed dog named Garm.

Cerberus appears in Dante's Inferno, guarding the third circle of Hell rather than the entire underworld. This is the circle of gluttony, and Cerberus is used to personify uncontrolled appetite.

Fluffy, the giant three-headed dog mentioned in Harry Potter and the Sorcerer's Stone, resembles Cerberus. Both Fluffy and Ceberus are lulled to sleep by music.