Cerberus was a three headed monster from the myths of    ancient Greece and ancient Rome. Its tail was a snake.

Cerberus was a guard dog. It guarded the gates of Hades,

also known as the Underworld.

One of the tasks of Hercules was to go to the Underworld and capture Cerberus. With the help of Hermes, messenger of the gods, Hercules entered the Underworld through a secret entrance.

When Hercules came upon Cerberus, the two attacked each other. They wrestled for hours. Hercules wore a thick lion's coat so that the snake/tail could not bite and poison him.

Eventually, Cerberus was so exhausted that he collapsed. Hercules had defeated the three headed monster.