Stephen Reeder Donaldson is an American fantasy, science fiction, and mystery novelist, most famous for The Chronicles of Thomas Covenant, his ten-novel fantasy series. His work is characterized by psychological complexity, conceptual abstractness, moral bleakness, and the use of an arcane vocabulary, and has attracted critical praise for its "imagination, vivid characterizations, and fast pace".

Donaldson earned his bachelor's degree from The College of Wooster and a master's degree from Kent State University. He currently resides in Albuquerque, New Mexico.

Born on May 13, 1947 in Cleveland, Ohio, Donaldson spent the years between the ages of 3 and 16 living in India, where his father worked as an orthopedic surgeon. In the United Kingdom, he is usually called "Stephen Donaldson" (without the "R"). He has also written non-fiction under the pen name Reed Stephens.