Cerberus
The Three-Headed Dog
Depending on the sources, some say Cerberus could have up to 100 heads. Most sources agree to only three. The center head was in the shape of a lion, while the other two were in the shape of a dog and a wolf. Cerberus has a brother, Orphus, which is also a monstrous dog with two heads. Similar to Cerberus is the Egyptian Anubis, the dog who guarded the tombs and conducted the souls to the underworld. The three heads were said to represent the past, the present and the time yet to come.
He is also the watchdog of Hell. He is often pictured with Hades, his master. He can be found on the banks of the river Styx, where he had the task of eating any mortals who attempted to enter, and any spirits who attempted to escape.