The Lernaean Hydra or Hydra of Lerna (Greek: Λερναῖα Ὕδρα, Lernaîa Hýdra), more often known simply as the Hydra, was a serpentine water monster in Greek and Roman mythology. Its lair was the lake of Lerna in the Argolid, which was also the site of the myth of the Danaids. Lerna was reputed to be an entrance to the Underworld[1] and archaeology has established it as a sacred site older than Mycenaean Argos. In the canonical Hydra myth, the monster is killed by Heracles, using sword and fire, as the second of his Twelve Labors.[2]
According to Hesiod, the Hydra was the offspring of Typhon and Echidna.[3] It possessed many heads, the exact number of which varies according to the source. Later versions of the Hydra story add a regeneration feature to the monster: for every head chopped off, the Hydra would regrow one or multiple heads.[4]
The Hydra had poisonous breath and blood so virulent that even its scent was deadly.[5]
The Hydra had many parallels in ancient Near Eastern religions. In particular, Sumerian, Babylonian, and Assyrian mythology celebrated the deeds of the war and hunting god Ninurta, whom the Angrim credited with slaying 11 monsters on an expedition to the mountains, including a seven-headed serpent (possibly identical with the Mushmahhu) and Bashmu, whose constellation (despite having a single head) was later associated by the Greeks with the Hydra. The constellation is also sometimes associated in Babylonian contexts with Marduk's dragon, the Mushhushshu.