There are many creatures in Tolkien’s Legendarium that come across as uncanny and downright scary. The Nazgûl definitely belong to this category. Also known as the Ringwraiths, they send panic and fear before them, and this name — Ringwraiths — has hidden clues to their nature.
Following the success of The Hobbit, Tolkien was asked to write the sequel to it: the publisher and the public wanted more adventures of the Hobbits. As the Professor began working on the follow-up to his story, the new tale, which eventually became The Lord of the Rings, was slowly diverging from the light tone of The Hobbit and the area of children’s literature into the darker and more sinister realm. One of the chief contributors to the darkness of the new tale were the Black Riders. Read more
The rider’s cloak streamed behind him, and his hood was thrown back; his golden hair flowed shimmering in the wind of his speed. To Frodo it appeared that a white light was shining through the form and raiment of the rider, as if through a thin veil.
(Fellowship of the Ring, p. 275) Read more