(Greek: Σ.Φ.Ο.Π., Σύλλογος Φιλάθλων Οπαδών Παναθηναϊκού, Syllogos Filathlon Opadon Panathinaikou, Panathinaikos Supporters Club) and stayed active for an unknown amount of time.

In order to organize trips for away matches and other events, the various fan clubs used to write in the two newspapers most read by Panathinaikos fans of the time, Athlitiki Iho (Greek: Αθλητική Ηχώ, Athletic Echo) and Panathinaika Nea (Greek: Παναθηναϊκά Νέα, Panathenaic News).

Notable clubs included: Ampelokipi, Zografou, Patissia, Gizi, Petralona, Cholargos, Peristeri, Nikaia-Koridallos, Patras and many more, most of which are still active today.

Since 1962–63 there had been thoughts of founding a universal club under the name of the stadium's gate where the team's most devoted supporters met, but at the time there were many difficulties.

Then, in 1966, after much effort, the "Syndesmos Filon Panathinaikou Athlitikou Omilou "I Thyra 13"" (Σύνδεσμος Φίλων Παναθηναϊκού Αθλητικού Ομίλου "Η Θύρα 13", Fan Club of Panathinaikos Athletic Club "Gate 13") first operated on November 19, 1966, on 68, Kolonos Str in Athens.

On November 27, 1966, a few days after the foundation of Gate 13, a bus carrying Panathinaikos fans from Athens to Veroia crashed, resulting in the death of two Panathinaikos fans, Giorgos Koskoros (Greek: Γιώργος Κόσκορος) and Dimitris Sarantakos (Greek: Δημήτρης Σαραντάκος) who was one of the founding members of Gate 13.

Gate 13 remains until today the loudest part of the stadium, with many flags and banners giving colour and character to the stand.

[1] Beyond the friendship with Ultras Rapid Wien, the closest active relations parts of Gate 13 share are with GNK Dinamo Zagreb, Bad Blue Boys and Roma, Curva Sud (Fedayn).

Over the years parts of Gate 13, had also friendships with groups from Real Madrid (Orgullo Vikingo) mainly during the 90s, Ajax Amsterdam (F-SIDE Amsterdam), Ferencváros, Hammarby IF FF, AS Saint-Étienne, Tottenham Hotspur F.C., Sporting CP, Club Atlético River Plate and Anadolu Efes S.K.