Elizabeth Cynthia Barr (born December 17, 1971), later known by her married name Beth Isaak, is an American former competition swimmer who was a backstroke specialist and Olympic silver medalist.As a 16-year-old, she represented the United States at the 1988 Summer Olympics in Seoul, South Korea.She who won a silver medal by swimming the backstroke leg for the second-place U.S. team in the women's 4×100-meter medley relay, together with teammates Janel Jorgensen (butterfly), Tracey McFarlane (breaststroke), and Mary Wayte (freestyle).Individually, she also competed in the women's 100-meter backstroke, finishing fifth in the event final with a time of 1:02.78, and the women's 200-meter backstroke, finishing fourth in 2:12.39.
Barr grew up in Pensacola, Florida, where she trained with PJC Aquatics (now known as Greater Pensacola Aquatic Club).As of 2008, she lives in Phoenix.