A rare title for the greatest of the Ringwraiths, leader of the Nine Riders or Nazgûl, and better known as the Lord of the Nazgûl. The usage of the title is unclear; it was given to him only once, when Frodo Baggins and his companions saw him leading a host out of Minas Morgul. The context there makes it unclear whether it was an actual title of the Witch-king, or simply a term arising in Frodo's imagination that reflected his own flight from the Black Riders and their Lord, who had pursued him out of the Shire to Rivendell.