In J. R. R. Tolkien's Midle-earth legendarium, the Nazgûl (from Black Speech nazg, "ring", and gûl, "wraith, spirit"; also called Ringwraiths, Ring-wraiths, Black Riders, Dark Riders, the Nine Riders, or simply the Nine) are nine undead human kings who have succumbed through greed to Sauron's power and attained immortality as wraiths bound to the power of the One Ring as servants of The Enemy. They are first mentioned in his book The Lord of the Rings, originally published in 1954–1955. The book refers to the Nazgûl as Sauron's "most terrible servants."