Olympique Lyonnais ([ɔlɛ̃pik ljɔnɛ]), commonly referred to as simply Lyon ([ljɔ̃]) or OL, is a men and women's French professional football club based in Lyon in Auvergne-Rhône-Alpes. The men play in France's highest football division, Ligue 1. Founded in 1950, the club won its first Ligue 1 championship in 2002, starting a national record-setting streak of seven successive titles. Lyon has also won eight Trophées des Champions, five Coupes de France, and three Ligue 2 titles.

Lyon has participated in the UEFA Champions League seventeen times, and during the 2009–10 season, reached the semi-finals of the competition for the first time after three previous quarter-final appearances. They once again reached this stage in the 2019–20 season. Olympique Lyonnais plays its home matches at the 59,186-seat Parc Olympique Lyonnais, commercially known as the Groupama Stadium, in Décines-Charpieu, a suburb of Lyon. The club's home colors are white, red and blue. Lyon was a member of the G14 group of leading European football clubs and are founder members of its successor, the European Club Association.

The club's nickname, Les Gones, means "The Kids" in Lyon's regional dialect of Franco-Provençal. They have a long-standing rivalry with nearby club Saint-Étienne, with whom they contest the Derby Rhône-Alpes. Lyon have been owned by Jean-Michel Aulas since 1987 before American businessman John Textor purchased the club in June 2022.

Olympique Lyonnais was initially formed under the multisports club Lyon Olympique Universitaire, which was originally formed in 1896 as Racing Club de Lyon. Following numerous internal disagreements regarding the cohabitation of amateurs and professionals within the club, then-manager of the club Félix Louot and his entourage contemplated forming their own club. On 3 August 1950, Louot's plan came to fruition when Olympique Lyonnais was officially founded by Dr. Albert Trillat and numerous others. The club's first manager was Oscar Heisserer and, on 26 August 1950, played its first official match defeating CA Paris-Charenton 3–0 in front of 3,000 supporters. In just the club's second year of existence, Lyon was crowned champion of the second division, securing promotion to the first division. The club maintained its first division place for the remainder of the decade, excluding a year's stint in the second division for the 1953–54 season.