According to Greek mythology, Cerberus is a three-headed dog which guards the entrance to the underworld where the dead are allowed to enter but no one is allowed to leave. Apart from its three heads, the Cerberus has the tail of a serpent, a mane of snakes and the claws of a lion. The name Cerberus is derived from the Greek word “Kerberos” meaning “spotted”. His three heads were supposed to denote the past, present and the future. They were also said to denote birth, youth and old age. The most powerful weapon for Cerberus was his stare which could turn anyone into stone. He had razor sharp teeth and his bite was also poisonous.