Panionios G.S.S. (Greek: Πανιώνιος Γυμναστικός Σύλλογος Σμύρνης - Panionios Gymnastikos Syllogos Smyrnis), the Pan-Ionian Gymnastic Association of Smyrna, is a Greek multi sport club founded in 1890. Originally based in Smyrna/Izmir, the club was uprooted in the population exchange between Greece and Turkey following the Asia Minor Catastrophe in 1922. It is now based in the Athenian suburb of Nea Smyrni, (New Smyrna) in Greece, where many of the refugees from Smyrna settled.
The Panionios football team has won the Greek Cup twice (1979, 1998) while the Panionios basketball team won the Greek Cup in 1991.