Григорий Просветитель
St. Gregory the Illuminator, the patron Saint of the Armenian Apostolic Church, and King Tiridates III of Armenia, the ruler of the time, played a pivotal role in the official Christianization of Armenia. St. Gregory the Illuminator became the organizer of the Armenian Church hierarchy. From that time, the heads of the Armenian Church have been called Catholicos and still hold the same title.