Hydra (HYE-druh). The Hydra was a many-headed monster slain by Heracles. It was related to the Chimaera and Cerberus. As one of his Labors, Heracles sought the Hydra's lair in the swamps of Lerna and forced it out into the open with flaming arrows. Wading bravely into the fray, he began to hack at the monster with his sword. But every time he cut off one head, two grew in its place. Eventually, Heracles called on his charioteer to bring a torch to cauterize the Hydra's severed neck each time a head was lopped. This prevented new heads from sprouting. And when the final head was chopped off and buried beneath a rock, the monster died.