The Lord of the Nazgûl, also called the Witch-king of Angmar, the Pale King, or Black Captain, is a fictional character in J. R. R. Tolkien's fantasy novel The Lord of the Rings. He was one of the Nine among Men that the dark lord Sauron gave Rings of Power, becoming Nazgûl or Ringwraiths. His ring gives him great power, but enslaves him to Sauron and makes him invisible. As a wraith, he had once established himself King of Angmar in the north of Eriador. In the events of the Lord of the Rings, he stabs the bearer of the One Ring, the Hobbit Frodo Baggins, with a Morgul-knife which would reduce its victim to a wraith. Much later, in his final battle, the Lord of the Nazgûl attacks Éowyn with a mace. The Hobbit Merry Brandybuck stabs him with an ancient enchanted Númenórean blade, allowing Éowyn to kill him with her sword.
In early drafts, Tolkien had called him the "Wizard King", and considered making him either a renegade member of the Istari, or an immortal Maia, before settling on having him as a mortal Man, corrupted by a Ring of Power given to him by Sauron. Commentators have written that the Lord of the Nazgûl functions at the level of myth when, his own name forgotten, he calls himself Death and bursts the gates of Minas Tirith with magical spells. At a theological level, he embodies a vision of evil similar to Karl Barth's description of evil as das Nichtige, an active and powerful force that turns out to be empty. The prophecy that the Lord of the Nazgûl would not die by the hand of Man echoes that made of the title character in William Shakespeare's Macbeth.