John Treadwell Nichols (born July 23, 1940, Berkeley, California) is an American novelist.
Nichols is the author of the "New Mexico trilogy", a series about the complex relationship between history, race and ethnicity, and land and water rights in the fictional Chamisaville County, New Mexico. The trilogy consists of The Milagro Beanfield War (which was adapted into a movie of the same title directed by Robert Redford), The Magic Journey, and The Nirvana Blues.
Two of his other novels have been made into films. The Wizard of Loneliness was published in 1966 and the film version with Lukas Haas was made in 1988. Another successful movie adaptation was of The Sterile Cuckoo, which was published in 1965 and was filmed by Alan J. Pakula in 1969.