Clube de Futebol Os Belenenses, commonly known simply as Belenenses (Portuguese pronunciation: [bɨlɨˈnẽsɨʃ]), founded in 1919, is one of the oldest Portuguese sports clubs. It is based in the Belém quarter of Lisbon, hence the club name, which translates as "The ones from Belém."

Belenenses won the 1945–46 Primeira Liga and 6 Championship of Portugal/Portuguese Cup titles.

The main activities of the club are football, handball, basketball, futsal, athletics, and rugby union. The club has won major national championships in all these sports, but remains best known for its original activity, football.

By 1933, the club was the most successful in Portugal with 3 pre-Liga tournaments and finishing as runner-up on two other occasions. Beleneneses was one of Portugal's "Big Four" from the advent of the Primeira Liga. They have won less honours since than the other three clubs.

They won the Primeira Liga once (1945–46), the only team, together with Boavista (in 2001), to do so outside the Big Three: (Benfica, F.C. Porto, and Sporting Clube de Portugal). On 14 December 1947, they were the first team to face Real Madrid at their newly inaugurated Santiago Bernabéu Stadium (then called Nuevo Estadio Chamartín), a friendly match that they lost 3-1 to Los Blancos.