Olganoth

Olganoth the Warmonger was a powerful warlord and a member of the Pact of Iron. In life, he was an Orcish warrior, who died in the heart of a heated battle, now known as the Slaughter of Emdel Field. So great was his wrath, his soul continued fighting, rapidly going from living, to disembodied spirit, to blood-soaked demon. He never stopped slaying those around him, friend or foe, entering the field of battle an Orc, and walking off it a Tanarukk, a fiendish corrupted creature. This change did nothing to dim his lust for blood, and only the comprable power of the other members of the Pact made him cease his conquest. He retreated to the Ring of Blood, his massive arena, turning his attention to bloodsport. He had dozens of prisoners dragged to him daily by his soldiers, and they all fell under his blade in the Arena.
He finally fell at the end of the Age of Iron at the hands of Saint Emalia, who became the first person to ever defeat him in single combat, sealing his soul eyond the mortal realms for all eternity.