Gregory of Cyprus (Greek: Γρηγόριος ὁ Κύπριος, romanized: Grēgorios ho Kyprios; c. 1241 – c. 1290) was Ecumenical Patriarch of Constantinople (as Gregory II) between 1283 and 1289.

Gregory was born in Lapithos, Cyprus. His name was originally George. His parents were middle class but of noble origin. He moved to Nicosia as a teenager seeking further education. Not satisfied by the level of education provided by local teachers in Greek, he became a student at a Latin school (available then as Cyprus was a Crusader kingdom). He had difficulty learning Latin and thus got only a superficial knowledge of grammar and Aristotle's Logic.

Still determined to get a decent education, he got on a ship to Acre, Palestine, where he arrived after three days. From there he travelled to Anaea in Anatolia and finally made it to Mount Galesios near Ephesos. He had heard a lot about the scholar Nicephorus Blemmydes but was disappointed by him and moved to Nicaea where he studied with George Acropolites. With the recapture of Constantinople by Nicaean forces in 1261, he moved there. Later he became a teacher, his students including Nikephoros Choumnos.

He became patriarch in 1283. The orthodox and the catholic churches had proclaimed their union in 1274 in the Second Council of Lyons, motivated more by the emperor's politics than by theological arguments. Gregory, contrary to his predecessor refused to accept the filioque clause added to the Nicene creed by the Roman Catholics. Gregory spoke of an eternal manifestation of the Spirit by the Son. Gregory's formula has been considered an Orthodox "answer" to the filioque, though it does not have the status of official Orthodox doctrine. Gregory's perception of Trinity was endorsed by the council of Blachernae in 1285.

Gregory of Cyprus' doctrine of an eternal manifestation of the Spirit is often interpreted by Orthodox theologians as being a significant influence on Gregory Palamas and the formulation of his Essence-Energy doctrine. Particularly Dumitru Stăniloae,^[1] John Meyendorff,^[2] and Vladimir Lossky, who states:

It is interesting to note that the distinction between the hypostatic existence of the Holy Spirit, proceeding from the Father alone, and his eternal shining forth – εἰς αἷδιον ἔκφανσιν – through the Son, has been formulated during the discussions which took place in Consantinople at the end of the 13th century, after the Council of Lyon. We can grasp here the doctrinal continuity: the defence of the procession of the Holy Spirit from the Father alone requires clarification on the διὰ υἱοῦ, and that latter opens the way to the distinction between essence and energies. It is not a “dogmatic development” but one and same tradition defended on different points by the Orthodox theologians, from saint Photius to Gregory of Cyprus and saint Gregory Palamas^[3]

Gregory wrote collections of proverbs, his own autobiography, and a series of rhetorical exercises, as well as hagiographical and doctrinal works. He also left a collection of letters.

• Paroemiae (Proverbs): Schneidewin, F. G.; von Leutsch, E. L., eds. (1839). Corpus paroemiographorum Graecorum. Vol. I. Göttingen. pp. 349–378. von Leutsch, E. L., ed. (1851). Corpus paroemiographorum Graecorum. Vol. II. Göttingen. pp. 53–92, 93–130 & 131–134.{{cite book}}: CS1 maint: location missing publisher (link)
• Epistola ad Joannem II sebastocratorem Thessaliae (Epistle to John II, sebastokrator of Thessaly): Rapp, C. (1988). "Ein bisher unbekannter Brief des Patriarchen Gregor von Zypern an Johannes II., Sebastokrator von Thessalien". Byzantinische Zeitschrift. 81 (1): 12–20. doi:10.1515/bz-1988-0204. S2CID 191479342.
• Tomus fidei (Explanatory tome of the Orthodox faith): Migne, J. P., ed. (1863). Patrologiae cursus completus. Series Graeca. Vol. CXLIV. Paris. pp. 233–246.{{cite book}}: CS1 maint: location missing publisher (link)
• Progymnasmata (Rhetorical exercises): Kotzabassi, S. (1993). "Die Progymnasmata des Gregor von Zypern". Ἑλληνικά. 43: 51–63.
• De vita sua (On his own life; autobiography): Lameere, W. (1937). La tradition manuscrite de la correspondance de Grégoire de Chypre Patriarche de Constantinople (1283-1289). Rome–Paris. pp. 177–191.{{cite book}}: CS1 maint: location missing publisher (link)
• Contra Synesium, sive comae encomium (Against Synesius; or, hair praise): Pérez Martín, I. (1996). "El Elogio de la cabellera de Gregorio de Chipre". El Patriarca Gregorio de Chipre (ca. 1240-1290) y la transmisión de los textos clásicos en Bizancio. Madrid. pp. 361–396.{{cite book}}: CS1 maint: location missing publisher (link)
• Vita sancti Lazari (Life of St. Lazarus): Delehaye, H. (1910). Acta Sanctorum Novembris. Vol. III. Bruxelles. pp. 588–606.{{cite book}}: CS1 maint: location missing publisher (link)
• Oratio antirrhetica contra Joannem Beccum (Discourse against John Bekkos): Kislas, Th.; Savvatos, Ch. (2012). "Discours antirrhétique contre les opinions blasphématoires de Bekkos". In Larchet, J.-C. (ed.). La vie et l'oeuvre de Georges/Grégoire II de Chypre (1241-1290) patriarche de Constantinople. Paris. pp. 166–256.{{cite book}}: CS1 maint: location missing publisher (link)
• Epistulae ad Theodoram Rhaulenam (Letters to Theodora Rhaulena): Kotzabassi, S. (2011). "Scholarly friendship in the thirteenth century: Patriarch Gregorios II Kyprios and Theodora Raoulaina". Παρεκβολαί. 1: 145–167.
• Encomium maris, sive de universa aquae natura (Sea praise; or, on the Nature of Water): Migne, J. P., ed. (1863). Patrologiae cursus completus. Series Graeca. Vol. CXLIV. Paris. pp. 433–443.{{cite book}}: CS1 maint: location missing publisher (link)

• Ostrogorsky, George (1956). History of the Byzantine State. Oxford: Basil Blackwell.
• Papadakis, Aristeides (1997) [1983]. Crisis in Byzantium: The Filioque Controversy in the Patriarchate of Gregory II of Cyprus (1283-1289) (Rev. ed.). Crestwood, NY: St. Vladimir's Seminary Press. ISBN 9780881411768.

• Myriobiblos
• Tomos of the Blachernae Council