Judith Tarr (b. Augusta, Maine, January 30, 1955) is an American author, best known for her fantasy books. She received her B.A. in Latin and English from Mount Holyoke College in 1976, and has an M.A. in Classics from Cambridge University, and an M.A. and Ph.D. in Medieval Studies from Yale University. She breeds Lipizzan horses at Dancing Horse Farm, her home in Vail, Arizona. The romantic fantasies that she writes under the name Caitlin Brennan feature dancing horses modeled on those that she raises.
Tarr collaborated with Harry Turtledove on the novel Household Gods. In addition, Tarr wrote stories which were included in the four-author collaborative War World novels, along with Susan Shwartz, S.M. Stirling, and Turtledove.