From The Lord of the Rings wiki
Saruman
Saruman the White was the leader of the Istari and the head of the White Council who ultimately succumbed to the corruption of the One Ring.
Saruman was an Istar, or Wizard, sent to Middle-earth to aid its inhabitants against the rising threat of Sauron. Initially, he served as the head of the White Council, working alongside Gandalf the Grey and other allies to oppose the shadow in the East. He resided in the fortress of Orthanc, located within the circle of Isengard, where he conducted extensive research into the history of the Rings of Power.
His downfall began when he became obsessed with the power of the enemy, leading him to use the palantir of Orthanc. Through this device, he was ensnared by Sauron and eventually betrayed his allies, seeking to claim the One Ring for himself to establish his own dominion. He transformed Isengard into a military base, breeding Uruk-hai to wage war against the kingdoms of men, most notably Rohan.
Following the defeat of his armies by the Ents and the efforts of characters such as Aragorn, Legolas Greenleaf, and Gimli, Saruman was stripped of his rank and staff by Gandalf. He was eventually killed in the Shire by his servant Grima Wormtongue, marking the definitive end of his influence in the War of the Ring.
