Mary Lou Foy (born August 17, 1944) is an American photojournalist. She served as Picture Editor at the Washington Post from 1990 to 2006 and was president of the National Press Photographers Association in 1992.
Foy attended Auburn High School and Auburn University, receiving a B.A. in journalism from the latter in 1966. She attended graduate school at the University of Florida in journalism and environmental engineering, and in 1971 became the first female photojournalist to work for the Gainesville Sun. In 1974, she joined the staff of the Fort Lauderdale Sun-Sentinel, and in 1976 became the first woman photojournalist on the staff of the Miami Herald.