One of the three great divisions of Christianity; the others are the Protestant churches and the Roman Catholic Church. The Catholic and Orthodox churches were originally united, but they parted in the eleventh century, when they differed over several points of doctrine, including the supreme authority of the pope, which Orthodox Christians reject.
- Albanian Orthodox Diocese of America
- American Carpatho-Russian Orthodox
- Antiochian Orthodox Christian
- Armenian Apostolic Church
- Armenian Church of America
- Byelorussian Orthodox
- Greek Orthodox Church
- Eastern Orthodox - Other
- Orthodox Church in America
- Russian Orthodox Church
- Serbian Eastern Orthodox Church
- Ukranian Orthodox Church
