Cerberus

Three heads guard the entrance to Hades, allowing the deceased to enter while blocking the living and preventing the dead from leaving. Cerberus is a single monstrous hound, commonly shown with three heads, a serpent or dragon tail, snakes rising from his back, and lion’s claws. Some accounts give him fifty or one hundred heads. He is also described as an eater of raw flesh, with dagger sharp teeth, a poisonous bite, and a bark like clashing bronze.

Cerberus is the offspring of Typhon and Echidna, the half serpent mother of several monsters. He belongs to the House of Hades and guards its entrance on the banks of the River Styx. Homer calls him the hound of Hades. In the myths of Herakles and Aeneas, he appears as the guardian that separates the world of the living from the realm of the dead.