Lycanthrope

Lycanthropes (from the Greek λυκάνθρωπος: λύκος, lukos, "wolf", and άνθρωπος, anthrōpos, man) were humans that were cursed and had the ability to shapeshift into wolf-like creatures known as Werewolves. The first of the Lycanthropes was Lycaon.

Description
Lycanthropes appear in many different cultures, more commonly known as werewolves, and they can only be killed by silver. In both myths and popular culture, there are many ways of becoming a werewolf, with the most well-known one (which is used in the series) being if one bites you.

History
During the Ancient Times, Zeus decided to dine with Lycaon, the King of Arcadia. To prove that Zeus really was who he said he was, Lycaon tried to feed him human flesh. Then he hired assassins to attack Zeus while he slept to test the limits of his immortality. Zeus became so enraged he slew Lycaon's sons with lightning bolts (except maybe for one) and made Lycaon the first Lycanthrope.

The Lost Hero
Lycaon and his Lycanthrope minions await Jason Grace, Piper McLean, Leo Valdez, and Coach Hedge when they were on the search for Aeolus. He orders his minions to kidnap Jason, and kill Leo and Piper. They are later defeated when the Hunters of Artemis arrive. Lycaon is the only one to escape.

They later reappear under the command of Khione at the Wolf House. Since Lycaon was formerly injured by Thalia, he is not present; however his minions are there to fight for him. When Leo is fighting Khione he uses silver hammers to smash any wolves that get in his way. He and Jason kill all of them, but Porphyrion brings them all back to life when he awakes. The Lycanthropes were either killed or scared off when Hera is freed and turns into her Divine Form.

Weakness
The Lycanthropes are immune to gold, bronze, steel, and iron. The only thing that can kill them is silver. They can also be hurt by fire, although not fatally, and it's possible they can be hurt or even killed by lightning.

Known Lycanthropes

 * Lycaon