One of the many titles used for the nameless Lord of the Nazgûl, master of the Ringwraiths and chief servant of Sauron. Of his origins little is known, though he was said to have been a sorcerer and a king before being ensnared by the Dark Lord. In about the year II 2250 he was granted one of the Nine Rings, and through that Ring Sauron enslaved his will. The power of his Ring extended his life, and he would rule over the other eight Ringwraiths for more than four thousand years.

During the later Second Age, Sauron ruled much of Middle-earth, especially in the East, and the dread Nazgûl worked his will, though we have few records of their doings in this time. The Second Age came to an end when Sauron was defeated by the Last Alliance, and after this time the Wraith-lord and his fellow Ringwraiths faded out of history for more than a millennium.

The dark spirit of Sauron reappeared in about the year III 1050, establishing a stronghold at Dol Guldur in southern Mirkwood, and as he did so, the Nazgúl once again appeared in Middle-earth. The Wraith-lord took on a new role at this time, being sent into the far North by his master to challenge the disunited Northern Dúnedain. He founded the realm of Angmar among the northern peaks of the Misty Mountains, and from there he waged war on the divided lands of Arnor. For nearly seven centuries he fought the Northern Dúnedain, and at last destroyed all three of their realms, before he himself tasted defeat. A force of Gondorians and Elves took revenge for the fall of the North-kingdom, and drove the Witch-king out of the North. It was at this time that the Elf Glorfindel spoke a prophecy that the Wraith-lord would not die by the hand of any man.

After his defeat in the North, the Wraith-lord returned to the Dark Land of Mordor and gathered his fellow Ringwraiths there. In the year III 2000, the Nazgûl emerged and attacked the Gondorian stronghold of Minas Ithil, which they succeeded in capturing two years later. Thereafter, the tower was given a new name, Minas Morgul, the tower of dark sorcery, and the Wraith-lord became its ruler. He would hold the Dead City for the next thousand years, until the close of the Third Age.

When Sauron discovered that his One Ring had been found again, and was associated with a land named 'Shire', he sent out his Nazgûl to locate and recover the Ring. The Wraith-lord led the Nine into the northern lands, and they came close to achieving their goal, but they were overwhelmed on the approaches to Rivendell and carried away by rushing waters. The Wraith-lord returned to Minas Morgul, where he readied for the War to come, and led out the Morgul-host to directly attack the Gondorian city of Minas Tirith beyond Anduin. Glorfindel's prophecy was fulfilled when the Wraith-lord faced a warrior of the Rohirrim who revealed herself to be no man, but the Shieldmaiden Éowyn. Aided by the Hobbit Meriadoc Brandybuck, she brought the millennia-long life of the Lord of the Ringwraiths to an end.