List of ecumenical patriarchs of Constantinople

The Ecumenical Patriarch of Constantinople (Greek: Οἰκουμενικός Πατριάρχης, romanized: Oikoumenikós Patriárchēs) is the archbishop of Constantinople and primus inter pares (first among equals) among the heads of the several autocephalous churches that comprise the Eastern Orthodox Church. The ecumenical patriarch is regarded as the representative and spiritual leader of the Eastern Orthodox Christians worldwide. The term ecumenical in the title is a historical reference to the Ecumene, a Greek designation for the civilised world, i.e. the Roman Empire, and it stems from Canon 28 of the Council of Chalcedon.

The patriarch's see, the Ecumenical Patriarchate of Constantinople, is one of the most enduring institutions in the world and has had a prominent part in world history. The ecumenical patriarchs in ancient times helped in the spread of Christianity and the resolution of various doctrinal disputes. In the Middle Ages, they played a major role in the affairs of the Eastern Orthodox Church, as well as in the politics of the Orthodox world, and in spreading Christianity among the Slavs. Currently, in addition to the expansion of the Christian faith and the Eastern Orthodox doctrine, the patriarchs are involved in ecumenism and interfaith dialogue, charitable work, and the defense of Orthodox Christian traditions.

Michael I of Constantinople (Cerularius or Keroularios; Greek: Μιχαὴλ Κηρουλάριος, romanized: Mikhaḗl Keroulários; c. 1000 – 21 January 1059) was the Ecumenical Patriarch of Constantinople from 1043 to 1059. His disputes with Pope Leo IX over church practices in the 11th century played a role in the events that led to the Great Schism in 1054.

Polyeuctus of Constantinople (Greek: Πολύευκτος; died 5 February 970) was Ecumenical Patriarch of Constantinople (956–970). His orthodox feast is on 5 February.

Nestorius of Constantinople (/ˌnɛsˈtɔːriəs/; Ancient Greek: Νεστόριος; c. 386 – c. 451) was an early Christian prelate who served as Archbishop of Constantinople from 10 April 428 to 11 July 431. He was a Christian theologian from the Catechetical School of Antioch, and several of his teachings in the fields of Christology and Mariology were seen as controversial and heretical, causing major disputes. In 431, he was condemned and deposed from his see by the Council of Ephesus, presided over by his archrival Cyril of Alexandria, but the counter-council led by John I of Antioch vindicated him and deposed Cyril in return. Nestorius refrained from attending both of these councils and instead sought retirement from the Byzantine Emperor.

Nestorius himself used the title Theotokos and did not advocate for its ban. His teachings included cautious usage of Theotokos ("God-Bearer"), used for Mary, mother of Jesus, in order that Christ's human and divine natures not be confused, as he believed Christ was born according to his humanity and not his divinity, which indicated his preference for the concept of the prosopic union of two natures (divine and human) of Christ, over the concept of a hypostatic union. He proposed instead the title of Christotokos ("Christ-bearer"). This brought him into conflict with Cyril of Alexandria and other prominent diophysite and miaphysite churchmen of the time, who accused him of heresy.

Eutychius of Constantinople (Greek: Εὐτύχιος, Eutychios; c. 512 – 5 April 582), considered a saint in the Catholic Church and Eastern Orthodox Christian traditions, was the patriarch of Constantinople from 552 to 565 and from 577 to 582. His feast is kept by the Orthodox Church on 6 April, and he is mentioned in the Catholic Church's "Corpus Juris". His terms of office, occurring during the reign of Emperor Justinian I, were marked by controversies with both imperial and papal authority.

Gregory of Nazianzus (Greek: Γρηγόριος ὁ Ναζιανζηνός, romanized: Grēgorios ho Nazianzēnos; c. 329 – 25 January 390), also known as Gregory the Theologian or Gregory Nazianzen, was an early Roman Christian theologian and prelate who served as Archbishop of Constantinople from 380 to 381. He is widely considered the most accomplished rhetorical stylist of the patristic age. As a classically trained orator and philosopher, he infused Hellenism into the early Church, establishing the paradigm of Byzantine theologians and church officials.

Gregory made a significant impact on the shape of Trinitarian theology among both Greek and Latin-speaking theologians, and he is remembered as the "Trinitarian Theologian". Much of his theological work continues to influence modern theologians, especially in regard to the relationship among the three Persons of the Trinity. Along with the brothers Basil of Caesarea and Gregory of Nyssa, he is known as one of the Cappadocian Fathers.