Saruman (Man of Skill) is one of the Istari, a weaked form of Maiar spirits sent by the Valar to oppose the will and might of Sauron in the Third Age of Middle-Earth. Saruman was appointed the head of the White Council. Saruman spent years studying the history and lore of the One Ring but kept his actions secret from the rest of the White Council.
During the events of Lord of the Rings Saruman was setting plans in motion to take the ring for his own. In an attempt to execute his plan of dominance, Saruman bred his own race of Uruk-hai, a race of orcs of great stature, speed, and strength with the ability to withstand the light of the sun. Saruman's Uruks clash with the fellowship at Amon Hen which results in the death of Boromir and capture of the hobbits Merry and Pippin. The Uruks are pursued by Aragorn, Legolas, and Gimli but the Uruks are overtaken by the Riders of Rohan and Merry and Pippin escape. Merry and Pippin reunite with Gandalf (who they believed dead) within Fangorn Forest and are put under the care of Treebeard. When Treebeard is informed of the depraved quest of Saruman's at the expense of the living trees of the forest the Ents are infuriated/rallied and march on Saruman's tower and courtyard of Orthanc. There Saruman is held captive until the arrival of Gandalf (now the White) along with the remainder of the fellowship (with the exception of Frodo and Sam) and Saruman's staff is broken (his power and standing in the White Council taken away) and Treebeard is put in charge of keeping him confined to the tower of Orthanc.
Treebeard being a creature of soft heart and forgiveness takes pity on Saruman and can not find it in his heart to keep him (Saruman) imprisoned and allows him (and his servant Grima (the Wormtongue)) to leave Orthanc. After his departure from Orthanc, Saruman flees to the Shire where he begins to gain power and influence and by gaining this foothold begins to spread his dominance over the irresolute hobbits, leading up to the events of "The Scouring of The Shire". After the downfall of Sauron the hobbits begin a lengthy return to the Shire which has now been twisted and corrupted in their absence into an industrial landscape by the wickedness of Saruman. The hobbit company (Frodo, Sam, Merry, and Pippin) begin to rally the hobbits and learn that Saruman is the culprit of mutilation of the once green and fertile countryside. The hobbits succeed in overthrowing the servants of Saruman and even in casting Saruman himself from the Shire. During Saruman's departure his servant (the beaten down and broken Grima) takes his vengeance upon Saruman for Saruman's years of abuse and scorn toward him by slitting his throat and Wormtongue himself is then felled by arrows of the hobbits while attempting his own escape.
*Actor Christopher Lee played Saruman The White in The Lord Of The Rings film trilogy directed by Peter Jackson. He killed off by Grima much earlier in story and the scouring of the Shire is omitted entirely. The theatrical cuts also seem to imply that he wishes to serve Sauron, rather than claim the ring for himself.