Magtheridon

From wow.incgamers.com

Ruling Pit Lord over the battered lands of Outland of the Burning Legion. He commanded the demons and Fel Orcs that had remained in Outland from his Black Citadel. Was later defeated by Illidan Stormrage, who was helped by the Blood Elves and Naga.

Magtherigon was captured by the Fel Orcs, and weakened in order use his blood to create more Fel Orcs. Their plans were foiled by Alliance and Horde heroes, who entered the prison of Magtheridon and slew him.