Who is the Lord of the Nazgûl?

The Lord of the Nazgûl is the Witch-king of Angmar.

He is the chief of the nine Ringwraiths and Sauron's most powerful servant among them. His personal name is never recorded in Tolkien's published works. Instead, he is identified by titles connected with his history, especially Witch-king of Angmar, Lord of the Nazgûl, and the Black Captain.

Sauron gave Rings of Power to nine mortal Men, transforming them over time into invisible wraiths bound to the One Ring's master. The Witch-king later established the realm of Angmar in the north and helped destroy the successor kingdoms of Arnor. His fortress and capital was Carn Dûm.

He leads the Nazgûl during the War of the Ring, stabs Frodo at Weathertop, and commands the assault on Minas Tirith. At the Battle of the Pelennor Fields in 3019, Merry's enchanted blade makes him vulnerable, allowing Éowyn to deliver the killing blow. Sauron is the Nazgûl's master, not their lord in the title used by the quiz.