She was played by Eve Gordon.
Joy was the matriarch of a family of werewolves, which Garth ends of joining when he is bitten and marries Bess, the daughter of Minister Jim Meyers and the stepdaughter of Joy. Under Jim's rule, the community operates under peace, but Joy had been committing murders in order to start a mass war. She even kidnapped Garth, Bess, and Sam, with plans to kill the couple and frame Sam and Dean for the murders to further her sinister plan, but Dean enters and stops her. At that moment, Joy transforms into her werewolf form, but to no avail, as Dean shoots and kills her.