Léon Marchand (French pronunciation: [leɔ̃ maʁʃɑ̃] ; born 17 May 2002) is a French swimmer. He is the World record holder in the long course 200 and 400 metres individual medley, and in the short course 200 metres individual medley; the Olympic record holder in the 200 and 400 metres individual medley, 200 metres butterfly and the 200 metres breaststroke; the European record holder in the long course 200 and 400 metres individual medley and the 200 meters breaststroke, in the short course 100 and 200 metres individual medley and the French record holder in the long course 200 and 400 metres individual medley, 200 metres butterfly and the 200 metres breaststroke, and in the short course 100, 200, 400 metres individual medley and the 200 metres breaststroke. At the 2024 Summer Olympics, he won gold medals in the 200 m medley, 200 metre breaststroke, 200 metre butterfly, and 400 metre medley. He became the fourth swimmer and third male swimmer in Olympic history to win four individual gold medals at a single Games.
As a member of the Arizona State University swim team, at the 2022 NCAA Division I Men's Swimming and Diving Championships, Marchand won NCAA titles in the 200 yard breaststroke and 200 yard individual medley. At the 2023 NCAA Division I Men's Swimming and Diving Championships, he won NCAA titles in the 200 yard breaststroke, 200 yard individual medley, and 400 yard individual medley. At the 2024 NCAA Division I Men's Swimming and Diving Championships in his last year before going pro, he won NCAA titles in the 200 yard breaststroke, 500 yard freestyle and 400 yard individual medley. He won with his college swim team the NCAA championship title for the first time ever.
