Hydras are large three-headed reptilian creatures that can be found throughout Tyria and the Fissure of Woe.
 List of hostile NPCs
- The Lernaean Hydra was a multi headed creature slain by Heracles (Labors of Hercules) for his second labor.
- All hydra bosses have a 3 part name, one name representing each head. Some or all of them are distorted and/or re-ordered phonetic versions of common expressions. For instance, Nayl Klaw Tuthan is a phonetic rendering of the idiom "nail, tooth, and claw."