Elizabeth Lyon Beisel (born August 18, 1992) is an American competition swimmer who specializes in backstroke and individual medley events. Beisel placed second in the 400m individual medley at the 2016 US Olympic Swimming Trials, qualifying for her third Olympic team. She has won a total of nine medals in major international competition, four gold, one silver, and four bronze spanning the Olympics, World Aquatics, and the Pan Pacific championships. Beisel competed in the 200-meter backstroke and 400-meter individual medley events at the 2008 Summer Olympics, placing fifth and fourth, respectively, in the world. She won the silver medal in the 400-meter individual medley and bronze in the 200-meter backstroke at the 2012 Summer Olympics.
Beisel was born in Saunderstown, Rhode Island in 1992, the daughter of Ted and Joan Beisel. She graduated from North Kingstown High School in North Kingstown, Rhode Island in 2010. Her mother was a college swimmer for the University of Rhode Island. From the age of 12 through high school, she competed for the Bluefish Swim Club while training under coach Chuck Batchelor. Beisel became a member of the U.S. national swim team when she was 13 years old.