Mary Louise Stepan (February 2, 1935 – December 15, 2021) was an American competition swimmer and Olympic medalist. As a 17-year-old, Stepan represented the United States at the 1952 Summer Olympics in Helsinki. She received a bronze medal as a member of the third-place U.S. team in the 4×100-meter freestyle relay, together with teammates Jackie LaVine, Jody Alderson and Evelyn Kawamoto. Individually, Stepan also competed in the women's 100-meter freestyle, advanced to the event final, and finished seventh overall with a time of 1:08.0. Stepan later married Richard Wehman and had four children. She was also a member of the United States Olympic Committee. Stepan died in Winnetka, Illinois, on December 15, 2021, at the age of 86.