Recalled to the battle by the unexpected advance of the Rohirrim, the Witch - king attacked Théoden, who had outrun his own riders. Snowmane, Théoden 's horse, was struck by a dart and fell upon Théoden. As the Witch - king approached him for the kill, Éowyn, the king 's niece, barred his way. She decapitated his mount, and the Witch - king replied with a powerful blow from his mace, breaking her arm and her shield. As he prepared to finish her off, the hobbit Meriadoc Brandybuck stabbed the back of the Witch - king 's knee with a Dúnedain dagger which bore enchantments deadly to the Witch - king. Éowyn then thrust her sword into the void between the Witch - king 's crown and torso. Her sword shattered but the Witch - king 's clothing fell to the ground and he vanished with a wailing cry.
who killed the witch king in the book
Éowyn Éowyn Meriadoc Brandybuck