AEK F.C. (Greek: ΑΕΚ ΠΑΕ, Αθλητική Ένωσις Κωνσταντινουπόλεως, Athlitiki Enosis Konstantinoupoleos, Athletic Union of Constantinople) abbreviated as AEK, known in European competitions as AEK Athens FC, is a major Greek association football club based in Nea Filadelfeia suburb of Athens.

Established in Athens in 1924 by Greek refugees from Constantinople, in the wake of the Greco-Turkish War (1919-1922), its name is a direct reference to the origins of the founders. The club's emblem is the double-headed eagle, used by the Palaiologos dynasty and traditionally by the Byzantine Empire, as a remembrance of the Byzantine legacy and the historical ties of the club. A.E.K. is one of the most successful teams in Greek football, winning 29 national titles (including 11 Championships, 14 Greek Cups, 1 League Cup and 3 Super Cups).

They are one of the most popular Greek clubs with millon of fans in Greece and Cyprus, such as in the Greek communities all over the world, mainly in Australia, United Kingdom and North America.

The club has appeared several times in European (UEFA Champions League and UEFA Europa League) competitions. They were the first Greek team to compete in the group stage of the UEFA Champions League in the early 90's, while they are until today the only Greek team which reached the semi-finals of the UEFA Cup (1976–77). They have reached also once the quarter-finals of the European Cup (1968–69) and twice the quarter-finals of the UEFA Cup Winners' Cup (1996–97, 1997–98). AEK is a member of the European Club Association.

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