Cerberus was the many-headed dog that guarded the entrance of the Underworld. He is mentioned as early as the Homeric poems, but simply as "the dog," and without the name of Cerberus. Hesiod, who is the first that gives his name and origin, calls him fifty-headed and a son of Typhaon and Echidna. Later writers describe him as a monster with only three heads, with the tail of a serpent and a mane consisting of the heads of various snakes. Some poets again call him many-headed or hundred-headed.
Cerberus kept watch at the mouth of the Acheron River. According to others he kept watch at the gates of the Underworld, into which he admitted the shades, but never let them out again.
- Cerberus at the Greek Myth Index