Hastur Lord is a science fantasy novel by American writers Deborah J. Ross and Marion Zimmer Bradley in the Darkover series. It was first published by in hardcover by DAW Books in 1996. The book falls in the part of the Darkover timeline that the author called "Against the Terrans: The Second Age ".

Marion Eleanor Zimmer Bradley was an American author of fantasy, historical fantasy, science fiction, and science fantasy novels, and is best known for the Arthurian fiction novel The Mists of Avalon and the Darkover series. Noted for the feminist perspective in her writing, her reputation has been posthumously marred by her daughter Moira Greyland's accusations of child sexual abuse, and for allegedly assisting her second husband, convicted child abuser Walter Breen, in sexually abusing multiple unrelated children.