Cerberus, the three headed dog, was the faithful servant to Hades, Greek god of the underworld.
He was charged with guarding the underworld from the living and devouring any dead soul who tried to return to the land of the living.
Besides his three heads, Cerberus had razor sharp teeth and snakes growing out his tail. He was known to be so vicious that even the gods and goddesses were afraid of him.
Hercules was the son of Zeus and a mortal woman, Alcmene, whom he seduced by disguising himself as her husband. Greek mythology would be pretty boring if Zeus had just kept it in his pants toga, but he seldom did.
Hera, the goddess wife of Zeus, was angry about all Zeus’s extra curricular activities. Sadly she took it out on his victims and children while remaining loyal to her husband.
Hera became a permanent enemy of Hercules, making several unsuccessful attempts to dispose of him. But Hercules had help from other gods and goddesses and became a mighty warrior, married a princess and fathered children.
One day as he returned from a battle, Hera saw her chance and made him go insane. In this state of mind, he killed his wife and children, thinking they were enemy soldiers.
When he recovered—because what would be the fun for Hera if he didn’t realize what awful thing he had done—he went to Delphi to consult the Oracle of Apollo. There he learned that he was the son of Zeus and as punishment for killing his family he would have to serve the cowardly King Eurysthesis and carry out Twelve Labors.
It took him eleven years to complete the first eleven Labors, helped along by some friendly gods and hindered by Hera every chance she got.
The final Labor, and the most difficult of all, was to cross into the underworld, kidnap Cerberus without using weapons and bring him to King Eurysthesis. With knowledge he gained from a mysterious Greek cult and a lion skin which gave him great powers, he was able to find the gate to the underworld, strike a bargain with Hades, and confront Cerberus.
Naturally Hercules emerged victorious because “The Eleven Labors of Hercules and the Time He Lost a Fight to a Dog” would not have made good epic poetry.
He brought the fearsome Cerberus to the cowardly King Eurysthesis who was terrified of the dog. In his fear he relieved Hercules of his service and allowed Cerberus to be returned to Hades.
Where he is today.