The Gunslinger by Stephen King is a horror fantasy novel, originally published in 1982 but then significantly revised in 2003. It is the 1st book in bestselling The Dark Tower series. Set in a science-fictional western world, it follows the story of Roland Deschain, the last descendant of the gunslingers, in a hunt for his arch enemy, “the man in black.”
The Little Sisters of Eluria by Stephen King is a fantasy horror novella originally published in 1998. It has been known as the (additional) prequel to The Dark Tower series, as book 0.5. It pictures the infancy of gunslinger Roland Deschain’s thrilling quest and the beginning of his chase for Walter o’Dim, the Man in Black.