Wurrzag
Wurrzag Ud Ura Zahubu, often known as "Da Great Green Prophet", is an enormously powerful Savage Orc Shaman, insane just like all Shamans (being a Savage Orc also didn't help).
However, he has great vision of the Orcish glory, leading armies to greatness before dissapearing to advance another plan for his kind. Right now, he is searching for the Once and Future Git and he has magic items created by Gork and Mork themselves to aid him.1,2
Unlike most wizards and shamans, Wurrzag doesn't stay at safe distance but charges into combat to blast the enemy with his Waaagh!-driven powers. The enemy wizards who tried to counter his blasts with their sorcery generally degenerate into rapid Squigs, allowing him to proceed unhindered. His abilities are so great that no army involving Wurrzag has known defeat; or at least, no-one has ever heard of one.1