His Holiness, the Catholicos of Armenia and of All Armenians (plural Catholicoi, due to its Greek origin) is the head archbishop of Armenia's national church, the Armenian Apostolic Church. It is one of the Oriental Orthodox churches that do not accept the decisions of the Council of Chalcedon. The first Catholicos of Armenia and of All Armenians was Saint Thaddeus, one of Jesus's apostles. It was Saint Thaddeus alongside Saint Bartholomew, another apostle of Jesus, who brought Christianity to Armenia in the 1st century. His Holiness is also sometimes called the "Catholicos of Etchmiadzin" after the city that is his see.
