Sarah Fredrika Sjöström (Swedish: ; born 17 August 1993) is a Swedish competitive swimmer specialising in the sprint freestyle and butterfly events. She is the current world record holder in the 50 metre freestyle (long course), the 100 metre freestyle (long course), the 50 metre butterfly (long course), the 100 metre butterfly (long course), and the 4×50 metre medley relay (short course). She is a former world record holder in the 50 metre freestyle (short course), 100 metre freestyle (short course), 100 metre butterfly (short course), and 200 metre freestyle (short course). She is the first Swedish woman to win an Olympic gold medal in swimming. She won the Overall Swimming World Cup in 2017 and 2018. In 2022, she became the first swimmer representing a country in Europe to win 10 individual World Championships gold medals. She currently represents Energy Standard in the International Swimming League.
Sjöström is the only female swimmer to win five individual medals at a single FINA World Aquatics Championships, a feat she accomplished in 2019. As of 2022, she has won a total of 19 individual medals at long course World Championships, more than any other female swimmer in history. Only Michael Phelps has won more individual medals (20). In 2021, Sjöström achieved a career total of over 1000 most valuable player points in the International Swimming League and became the first swimmer in history to do so. In 2022, she became the first swimmer from any country to win a total of 28 medals at LEN European Aquatics Championships. She has won 112 medals at Swimming World Cups.
In January 2022, Sjöström announced her engagement to her boyfriend of ten years, Swedish fencer Johan de Jong Skierus.