Sport Lisboa e Benfica (Portuguese pronunciation: [sɨˈpɔɾ liʒˈβoɐ i βɐ̃jˈfikɐ] ), commonly known as Benfica, is a professional football club based in Lisbon, Portugal, that competes in the Primeira Liga, the top flight of Portuguese football.

Founded on 28 February 1904, as Sport Lisboa, Benfica is one of the \"Big Three\" clubs in Portugal that have never been relegated from Primeira Liga, along with rivals Sporting CP and FC Porto. Benfica are nicknamed As Águias (The Eagles), for the symbol atop the club's crest, and Os Encarnados (The Reds), for the shirt colour. Since 2003, their home ground has been the Estádio da Luz, which replaced the larger, original one, built in 1954. Benfica is the most supported Portuguese club and the European club with the highest percentage of supporters in its own country. In 2006, Benfica had an estimated 14 million supporters worldwide, and in February 2025 it reached 400,000 club members, making them the largest sports club in the world by membership. The club's anthem, \"Ser Benfiquista\", refers to Benfica supporters, who are called benfiquistas. \"E pluribus unum\" (\"Out of many, one\") is the club's motto; Águia Vitória, the mascot.

With 87 major trophies won, Benfica is one of the two most decorated clubs in Portugal. They have won 84 domestic trophies: a record 38 Primeira Liga titles, a record 26 Taça de Portugal, a record 8 Taça da Liga, 9 Supertaça Cândido de Oliveira and 3 Campeonato de Portugal. Internationally, they won the Latin Cup in 1950 and back-to-back European Cups in 1961 and 1962 – both unique feats in Portuguese football – and were runners-up at the Intercontinental Cup in 1961 and '62, at the European Cup in 1963, '65, '68, '88 and '90, and at the UEFA Europa League (formerly the UEFA Cup) in 1983, 2013 and '14. Benfica's ten European finals are a domestic record and ranked seventh all-time among UEFA clubs in 2014. Noncompetitively, Benfica is honoured with the Portuguese Orders of Christ (Commander), of Merit (Officer), and of Prince Henry.

Benfica was voted 12th in FIFA Club of the Century and ranked 9th in the IFFHS Top 200 European clubs of the 20th century. In UEFA, Benfica is 8th in the all-time club ranking and was 20th in the club coefficient rankings at the end of the 2023–24 season. In the UEFA Champions League (formerly the European Cup), Benfica have the second most participations (42) and are the Portuguese club with the most wins (130). In this tournament, they hold the overall record for the biggest aggregate win, achieved in 1965–66. Moreover, Benfica hold the European record for the most consecutive wins in domestic league (29), where they became the first undefeated champions, in 1972–73.