The Assyrian Church of the East also called Holy Apostolic Catholic Assyrian Church of the East is a Christian church. It is one of the earliest churches to separate from the larger Church. It traces its origins to the See of Seleucia-Ctesiphon, started by Saint Thomas the Apostle as well as Saint Mari and Addai as shown in the Doctrine of Addai. This church is sometimes known as the "Nestorian Church", the "Syrian Church" or the "Persian Church." The church is currently headed by Mar Dinkha IV. 