Patriarch of the Church of the East

The patriarch of the Church of the East (also known as patriarch of the East, patriarch of Babylon, the catholicos of the East (ancient Greek: καθολικός katholikós, all-encompassing [καθ- + ὅλου + -ικός]) or the grand metropolitan of the East) is the patriarch, or leader and head bishop (sometimes referred to as Catholicos or universal leader) of the Church of the East. The position dates to the early centuries of Christianity within the Sassanid Empire, and the Church has been known by a variety of names, including the Church of the East, Nestorian Church, the Persian Church, the Sassanid Church, or East Syrian.

Source: Wikipedia — Patriarch of the Church of the East (CC BY-SA 4.0)