Echidna, monster of Greek mythology, half woman, half serpent. Her parents were either the sea deities Phorcys and Ceto (according to Hesiod’s Theogony) or Tartarus and Gaia (in the account of the mythographer Apollodorus); in Hesiod, Tartarus and Gaia are the parents of Echidna’s husband, Typhon. Among Echidna’s progeny by the 100-headed Typhon, were Ladon (the dragon who protected the Golden Apples of the Hesperides), another dragon who protected the Golden Fleece, the Hydra, the goatlike Chimera, and the infernal hounds Orthus and Cerberus. The Sphinx and the Nemean lion, both sired by Orthus, were also among her offspring.