Cerberus

Cerberus (Kerberos) was the gigantic, three-headed hound of Hades which guarded the gates of the underworld and prevented the escape of the shades of the dead. Cerberus was depicted as a three-headed dog with a serpent's tail, mane of snakes, and a lion's claws. According to some he had fifty heads although this count may have included the serpents of his mane.

Cerberus (Kerberos) name perhaps means "Death-Daemon of the Dark" from the ancient Greek words kêr and erebos.