Saruman

Saruman the white (also known as Curumo, Curunir, the skilled one), former Maiar of Aule, was the leader of the Istari sent to Middle Earth to battle Sauron. He became obsessed with the Rings of power and, having studied much of the ancient lore that was related to them, he was able to use his magical powers to drive Sauron out of Dol Guldur. Gradually, he succumbed to the Ring's spell, and he desired it for himself. Even when Sauron held him under his sway, Saruman dreamt of laying his own hands on the Ring instead of surrendering it to Sauron. He gathered armies of orcs, uruk-hai and dunlendings to help him take over Middle Earth. He made a big mistake when he used Orthanc palantir. Sauron, who also had a palantír, caught him and enslaved his will. So it came to be that the leader of the Istari became one of Sauron's allies.

However much power Saruman, no longer the White One, but Saruman of Many Colors, may have had, he could but stare from the lofty turrets of Orthanc as the Ents destroyed Isengard and filled the valley of the Isen with raging floodwaters. When Gandalf finally stripped Saruman of all power and authority, he was not humbled, but fled to the Shire with a few remaining rascals, and, calling himself Sharkey, started plundering and despoiling the land. Eventually he was murdered by Grima Wormtongue.

He thought that the name Sharkey, which he had been given by the orcs, was a sign of affection from their side. He did not know that sharkû means "old man" in black speech.