Cerberus in Greek and Roman mythology, is a three hound which guards the gates of Hades, to prevent those who have crossed the river Styx from ever escaping. In most works the three-heads each respectively see and represent the past, the present, and the future, while other sources suggest the heads represent birth, youth, and old age. The task of capturing Cerberus alive, without using weapons, was the final labour assigned to Heracles by King Eurystheus. He sucseded in doing so and became the most notable hero in Greek Mythology.