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Grima Wormtongue
Grima Wormtongue was the treacherous chief advisor to King Theoden of Rohan who secretly served the wizard Saruman the White.
Role in Rohan
Grima Wormtongue served as the primary counsellor to King Theoden in the golden hall of Meduseld. Under the influence of Saruman, Grima used his position to weaken the King through poisonous words and manipulative counsel, effectively paralysing the defences of Rohan while the wizard sought to expand his power from Isengard. His influence was only broken when Gandalf the Grey arrived and restored the King to his senses.
Later Years
Following his expulsion from Edoras, Grima became a broken servant to Saruman, eventually following him to the Shire during the War of the Ring. His resentment towards his master culminated in the death of Saruman at Bag End, where he killed the wizard before being slain himself by hobbit archers. His actions throughout the saga demonstrate the corrupting influence of the dark forces threatening the free peoples of Middle-earth, often contrasted against the noble resolve of heroes like Aragorn.