Witch-king's Fellbeast

The Witch-king's Fell Beast is a conjectural name of the gigantic flying wyvern-like creature on which the Witch-king of Angmar rode on during the War of the Ring in Middle-earth.

The Witch-king's Fell Beast was the largest of these creatures. It was, like all fell beasts in Mordor, fed foul meats by Sauron himself.

Although mainly riding upon a horse for the majority of the trilogy, the Witch-king takes up the Fell Beast during the end of the War of the Ring. When the Rohirrim arrived at the Fields of Pelennor, the Witch-king quickly rode off and mounted the Fell Beast. In battle, he shot King Théoden's horse, which fell and pinned the King to the ground. Landing on the fallen king, the Fell Beast dug its claws into the flesh of Snowmane. Dernhelm (who revealed herself as Éowyn) defended the dying Théoden, and challenged and beheaded the beast.

Even headless, the beast yet lived a few seconds before it died. Its master, the Witch-king, furiously attacked Éowyn, and almost killed her, but she survived and eventually killed him with the help of the hobbit Merry.

Not more than ten days later, Sauron himself would be destroyed, and all the remaining fell beasts would perish in the ruin of Mordor, along with their unearthly masters.

Behind the Scenes
In The Two Towers movie, in the fell beast's first appearance, it flies over Osgiliath that is being attacked by Mordor, and it almost captures the hobbit Frodo Baggins, after the Witch-king senses that the One Ring was with the halfling. But before the fell beast attacks Frodo, the other hobbit Samwise Gamgee saves him, and Faramir of Gondor shoots with an arrow the fell beast's neck. Frightened, the creature flies into Mordor.

It was especially prominent during the Battle of the Pelennor Fields, where it, along with the other fell beasts, slaughtered many Gondorian soldiers, grabbing them and their horses with its powerful claws and throwing them down the floor in the air. Later, when the Rohan army arrived to help Gondor, the Witch-king commanded the fell beast to attack King Théoden of Rohan, and feast on his flesh.

The fell beast attacked and quickly killed Snowmane, Théoden's horse. The horse fell on Théoden, crushing him.