Hydras are multi-headed serpents that can be magically summoned from other planes of reality. According to the description for Serpent's Sparker, the original Hydra was defeated centuries ago by the hero Bul-Kathos. The great serpent was said to spawn two heads for every one that was severed. In order to defeat it, the mighty nephalem supposedly pitched the beast into a roaring bonfire.
- For the Diablo I spell, see Guardian (spell).
- For the Diablo II skill, see Hydra (Diablo II).
- For the Diablo III skill, see Hydra (Diablo III).