Théoden

Théoden was the King of Rohan in the years leading up to the War of the Ring.  Influenced almost from the start by Grima Wormtongue, his advisor and secret servant of Saruman the White, Théoden opposed the actions of Gandalf until the uncovering of Grima and Saruman's plot, whereupon he rose from his throne in great shame and energy (especially for one so old - he was nearly 80) and offered his army for service in combat against Saruman and his army of orcs and men.

Théoden won great glory in the subsequent Battle of Helm's Deep and went on to lead the army of Rohan out onto the fields of Pelennor to defend the great city of Gondor against the dark forces of Sauron.  He was slain by the Witch-king, the Leader of the Ring-wraiths.