Who is the king of Rohan during the War of the Ring?

The king of Rohan during the War of the Ring is Théoden. He rules the horse-lords from Edoras and leads them through the kingdom’s crisis against Saruman and Sauron’s forces.

When Gandalf first meets Théoden in The Two Towers, the king is elderly, weakened, and heavily influenced by Gríma Wormtongue, an agent working for Saruman. Gandalf breaks that influence and restores Théoden’s will. Théoden then rejects Saruman’s manipulation and resumes active leadership of Rohan.

Théoden plays a major role in the defense of Helm’s Deep, where Rohan withstands Saruman’s army. Later, despite his age, he rides with the Rohirrim to Gondor’s aid. He dies during the Battle of the Pelennor Fields after charging into battle against Sauron’s forces.

Éomer is Théoden’s nephew and successor, while Éowyn is his niece and a shieldmaiden of Rohan. Gríma is his counselor and betrayer, not a king. Théoden’s son Théodred dies before him, making the succession crisis especially important to Rohan’s story.