Catholicos of the East

Catholicos of the East is an ecclesiastical title used by Eastern Churches. The title Catholicos, or "universal leader", is used in several Eastern Christian churches and implies a degree of sovereignty and . The designation "Catholicos of the East" originated in the see of Seleucia-Ctesiphon, the capital of Persia, center of the Church of the East since the early days of Christianity in Persia.

In the Church of the East, also known as the Nestorian Church, "Catholicos of the East" was one of the titles borne by the Bishop of Seleucia-Ctesiphon, who was the designated Patriarch of the Church of the East. It is still used in two successor churches, the Assyrian Church of the East and the Ancient Church of the East, the heads of which are known as Catholicos-Patriarchs.

Later, in the seventh century, the minority Syriac Orthodox Christians who lived in Persia began using the title for its Maphrian, who was originally the head of the Syriac Orthodox Christian community in Nestorian-dominated Persia. This office ranked second in the Syriac Orthodox church hierarchy after the Syriac Orthodox Patriarch of Antioch, until it was abolished in 1860. Today, the title is known as Catholicos of India.

The Saint Thomas Christians remain in communion with the Church of Antioch until their encounter with the Portuguese in 1599. There after the Christians of St Thomas had been influenced by many belief streams at different points of time. These influences have later resulted in serious rifts and in the breaking down of the monolithic apostolic church to different fragments under different faith stream. They were organised as a Church in the 8th century, served by foreign bishops and with a hereditary local chief called Arkadiyokon or Archdeacon. In the 16th century the overtures of the Portuguese padroado to bring the Saint Thomas Christians into the Catholic Church led to the first of several rifts in the community and the establishment of Roman Catholic and Malankara Church factions.Since that time further splits have occurred, and the Saint Thomas Christians are now divided into several Eastern Catholic, Oriental Orthodox, and independent bodies, each with their own liturgies and traditions.

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