KERBEROS (or Cerberus) was the gigantic hound which guarded the gates of
Haides. He was posted to prevent ghosts of the dead from leaving the underworld.
Kerberos was described as a three-headed dog with a serpent's tail, a mane of
snakes, and a lion's claws. Some say he had fifty heads, though this number
might have included the heads of his serpentine mane.