Deucalion Mars, real name unknown, was the former leader of the infamous Alpha Pack, which terrorized many packs across the country after he lost his eye sight. Once a man of peace, he sought to make a pact with hunters and werewolves alike to stop the bloodshed between their kind, only to be betrayed by Gerald Argent, blinded, and forced out of his pack.
However, after his encounter with Scott McCall and the Darach, Scott managed to return Deucalion's eyesight and allowed the once enraged Alpha a chance at redemption. Since the return of his sight he has been once again collecting abandoned omegas and alphas, this time in hopes of sheltering them from hunters or other werewolves who might savage them when they're alone. He has also since take up Buddhism to compliment his new pacifist lifestyle.
He, like Scott, is a Royal Breed alpha werewolf. Though he awoke long before Scott, and is perhaps the strongest werewolf in the series.