3. The Witch-King of Angmar (Lord Of The Rings)
Once a great king and sorcerer in Angmar, along with eight other powerful lords, the Witch-King was given a ring of great power - his was the greatest of his fellows. The giver, Sauron, knew full well that the rings would enslave the kings, binding them to the Dark Lord's will and turning them into undead wraiths. The Witch-King became a powerful warrior, feared across the lands, and he ultimately took control of Mordor and ruled it brutally with his dark magic. His appearance alone is enough to send fear in to almost any opponent (even beneath his intimidating helmet and haunting gowns, he looks terrifying). But when you consider his power, his skills as a fighter and his ruthlessness, you have a being more than worthy for recruitment in to the Sinestro Corps. Giving him another ring with even more power than the one he already possessed would make him a truly deadly foe.