Cerberus: Hades' Three-Headed Rottweiler

Cerberus is the guard dog of the gates of the underworld. It prevents those who have crossed the river styx from ever escaping. The most bad-ass dog in the world, it is one of the offsprings of Echidna, a hybrid half-woman and half-serpent, and Typhon, a fire-breathing giant whom even the Greek gods feared. Hercules'' final labour was capturing Cerberus without using any weapons. Guess how hard would that be?