Lycaon was the First King of Arcadia, according to Ancient Greek mythology, and one of the earliest recorded Werewolves. When Lycaon attempted to feed Zeus a meal of human flesh, the god turned him and his sons into wolves. Other versions have Lycaon sacrificing a child or even his own son to Zeus, with the same result. In both instances, abstaining from human flesh for ten years allowed the king to return to his human form.
His name, if not necessarily the origin of, is at least connected to the term Lycanthrope.