Sarah Fredrika Sjöström (born 17 August 1993) is a Swedish competitive swimmer specialized in sprint freestyle and butterfly events. She is the current world record holder in the 50-meter freestyle (long course), the 100-meter freestyle (long course), the 200-meter freestyle (short course), the 50-meter butterfly (long course), and the 100-meter butterfly (long course and 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 and she has won 10 individual World Championship 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 and as of 2019, she has won a total of 16 individual medals at long course World Championships, more than any other female swimmer in history. Only Michael Phelps has won more individual medals (20).