AD&D - New World
The Wolf of Arcworth
Once a human wizard named Nemonad, the Wolf of Arcworth was a companion of Edrick, Half-Ogre until he revealed himself to be an undead lich and an agent of chaos. The battle between Edrick and the Wolf (and the agents of Law and Chaos) directly led to the great disaster and the Chaos Taint that has forever changed the magic of Ur.
It is believed that the Wolf was destroyed when his phylactery — a powerful staff he used to cast his dark magic — was smashed by Edrick.