Éowyn is the Rohirrim woman who helps defeat the Witch-king of Angmar.
During the Battle of the Pelennor Fields, Éowyn disguises herself as the Rider Dernhelm and secretly joins Rohan’s military force. She confronts the Witch-king after he mortally wounds King Théoden. His claim that no living man can hinder him echoes an earlier prophecy that he would not fall by the hand of man.
Éowyn reveals her identity and attacks him, while the Hobbit Meriadoc Brandybuck—Merry—strikes the Witch-king with an enchanted Barrow-blade. That blow weakens or makes him vulnerable, allowing Éowyn to deliver the final sword thrust. Thus, both Éowyn and Merry are essential to his destruction.
Éowyn is Théoden’s niece, Éomer’s sister, and a noblewoman of Rohan who calls herself a shieldmaiden. The other options are not Rohirrim women involved in this scene: Rosie Cotton is a Hobbit, while Galadriel and Arwen are Elves. In Peter Jackson’s films, Éowyn’s role remains central, though some surrounding details differ from the book.