Who fought the hydra?

The Hydra was fought by the Greek hero Heracles (Hercules) as one of his Twelve Labors. This multi-headed serpent-like monster resided in the swamp of Lerna and was notorious for its regenerative ability; when one head was cut off, two more would grow in its place. Heracles ultimately defeated the Hydra by using fire to cauterize the necks after decapitating each head, preventing them from regrowing. He then buried the immortal head under a heavy rock to ensure it could not return.