The Big Three is the nickname of the three most successful and biggest football clubs in Portugal. The teams of S.L. Benfica and Sporting CP, both from Lisbon, and of FC Porto, from Porto, have a great rivalry and are usually the main contenders for the Primeira Liga title. They share all but two of the Portuguese Football Championships ever played, and generally end up sharing the top three positions. None of them has been relegated from the Primeira Liga either, having been participants in all editions since its first season in 1934–35. Benfica's lowest position was 6th in 2000–01, while Porto's 9th place finish in 1969–70 is the closest any of the three sides have come to relegation. Sporting's worst finish was a 7th place finish in 2012–13.

Sport Lisboa e Benfica, 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.