Lycaon is the first lycanthrope (werewolf) and a servant of the earth goddess, Gaea.
Lycaon was once a human king of Arcadia, the son of Pelasgus and Meliboea. Lycaon tested Zeus, who was a guest, by serving him human meat, including meat from one of his own sons. He also ordered assassins to attack Zeus while he slept to test his immortality. Zeus became angry as a result of Lycaon's actions. As punishment, he turned Lycaon into a wolf-man and killed all of his fifty sons with lightning bolts, except possibly Nyctimus, who was the slaughtered child. The Greeks named werewolves Lycanthropes after him, the first werewolf. It is hinted that Lupa has animosity towards him, since she is the mother of wolves.
(Thanks to gforce151 for requesting this creature!)