Kathryn M. "Kathy" Daynes (born 1946) is a professor of history at Brigham Young University (BYU) and a historian of Mormonism, specializing in Mormon polygamy. She was president of the Mormon History Association in 2008 and 2009.
Daynes began her studies as an undergraduate at BYU in 1964. However, she interrupted her studies and resumed them about ten years later at DePauw University, where she received her bachelors in history. She then went on to receive an M.A. and a Ph.D. in history, both from Indiana University, completing the latter in 1991. Daynes has been an instructor or faculty member at BYU since 1991.
Daynes is married to Byron (Bill) Daynes, a professor of political science at BYU. They are the parents of three children. Daynes was appointed the director of the Center for Family History and Genealogy at BYU in 2007.