Athlitiki Enosis Konstantinoupoleos (Greek: Αθλητική Ένωσις Κωνσταντινουπόλεως), more commonly referred to as AEK or in European competitions as AEK Athens, the Athletic Union of Constantinople, is a sports club based in the city of Athens, Greece.

The club was founded on 13th April 1924 in Athens by _Greek refugees from Constantinople (now Istanbul) in the wake of the Greco- Turkish War and subsequent population exchange. The large Greek population of Constantinople , not unlike those of the other Ottoman urban centres, continued its athletic traditions in the form of numerous athletic clubs. Clubs such as Enosi Tataoulon (Ένωση Ταταούλων) from the Tatavla district, Megas Alexandros (Μέγας Αλέξανδρος) of Vathyriakos, and Hermes (Ερμής - Ermis) of Galata existed to promote Hellenic athletic and cultural ideals; Hermes, one of the more popular clubs, was formed in 1875 by the Greek community of Pera (Galata). Forced by the Kemalist regime to change its name to Pera Club in 1921, many of its athletes fled during the population exchanges at the end of the Greco-Turkish War, and settled in Athens and Thessaloniki.

The founders of AEK established the club with the intention of providing athletic and cultural diversions for the thousands of predominantly Constantinopolitan and Anatolian refugees who had settled in the new suburbs of Athens (Nea Filadelfeia, Nea Ionia, Nea Chalkidona, Nea Smyrni, e.t.c.).