"They were once Men. Great kings of Men. Then Sauron the Deceiver gave to them nine rings of power. Blinded by their greed, they took them without question, one by one falling into darkness. Now they are slaves to his will. They are the Nazgul, Ringwraiths, neither living nor dead. At all times they feel the presence of the Ring, drawn to the power of the One."
The Nazgûl (or named Ringwraiths, sometimes written Ring-wraiths; also referred to as the Black Riders or as the Nine; or the Nunbolg; or the Ulairi in Quenya) were the dreaded ring-servants of the Dark Lord Sauron in Middle-earth throughout the Second and Third Ages, and in the later years of the Third Age they dwelt in Minas Morgul and Dol Guldur.