Théoden

Théoden is a supporting character in The Lord of the Rings series, appearing in The Two Towers and The Return of the King. He is the ruler of Rohan who looks out for his people and has fostered his niece, Eowyn, and their nephew Eomer. He is th father of Théodred, the husband of Elfhild, brother to Théodwyn, and uncle to Éowyn and Éomer.

Background
Théoden was the seventeenth king of Rohan. He was married to the queen, Elfhild and had with her one son, named Théodred. Uncle to Éowyn and Éomer, he adopted them after the deaths of their parents. Raising them as his own children, Éowyn and Éomer were raised alongside their cousin, Théodred, who loved both as a sister and a brother.

Before the series, Théoden's mind was poisoned by Saruman, while being influenced by Grima Wormtongue's dangerous lies.

The Two Towers
Théoden did not appear in The Fellowship of the Ring and did in the second series.

The Two Towers
Theoden was under the influence of his one-time friend, Saruman and Grima Wormtongue. Unlike the books, Theoden is actually poisoned by Saruman's magic rather than being under just the influence of Grima Wormtongue. He supposedly banished Eomer, the only surviving heir, but in reality, was Wormtongue's himself. When Gandalf, Aragorn, Gimli and Legolas arrived, Gandalf as the whtie wizard rescued Theoden from Saruman's control. He learns of his son's death and is sad to have to bury his own son. Seeing Saruman's oncoming attack, Théoden takes his remaining people to Helm's Deep.

After the attack on the Wargs, Theoden has Eowyn guide the women, children, and the wounded to Helm's Deep, where he takes a final stand, following Aragorn, who was thought to be dead, into battle. Eomer returns to help his uncle and their forces, followed by Gandalf.

Return of the King
Theoden then accompanies the Fellowship to Isengard as the fellowship is reunited with their missing companions Meriadoc Brandybuck and Peregrin Took. During a confrontation with Saruman, he attempts to use his soft-speaking, enchanting voice with Théoden talking to have peace and council like the ould days. However, Théoden is unswayed and retorts that they will have peace when the war is over and infuriates the White Wizardwhen placed in his own giblets and letting the crows attack him.