CERBERUS

Cerberus is the three headed dog that guards the gates to the underworld and keeps the living from entering the world of the dead. Psyche had to pass this dog on her journey to get the beauty lotion from Proserpina. Cerberus shows up in a couple places that are familiar to everybody. First of which would be in Hercules. Hercules had to capture the dog and bring him back to King Eurystheus.
Another place in modern culture where we see the three headed beast is in Harry Potter and the Sorcerers Stone. In this book, Harry, the hero, has to go through many trials to get to the Sorcerer's Stone, a stone that gives everlasting life. In a way, this is like going into the Underworld because he is going down below the castle. And wouldn't you know it, he has to get past a big three headed dog that just so happens to be blocking the trap door (gate) to the stone. The dog in Harry Potter is affectionately named Fluffy.

I thought it was interesting how Harry Potter incorporated the three headed dog on the journey to the underworld.

Here is a link to another blog that talks alot about Cerberus and his different forms if you are interested.

http://www.slice-o-life.com/creepbox/?startpos=5