I was informed by a viewer this is Saint Gregory of Great Armenia. From the Wikipedia: St. Gregory of Nyssa (Greek: Ἅγιος Γρηγόριος Νύσσης; Latin: Gregorius Nyssenus; Armenian: Գրիգոր Նիւսացի Grigor Niwsats'i; Arabic: غريغوريوس النيصي) (c 335 – after 394) was a Christian bishop and saint. He was a younger brother of Basil the Great and a good friend of Gregory Nazianzus. His significance has long been recognized in the Eastern Orthodox, Oriental Orthodox, Eastern Catholic and Roman Catholic branches of Christianity. Some historians identify Theosebia the deaconess as his wife, others hold that she, like Macrina the Younger, was actually a sister of Gregory and Basil.
Gregory along with his brother Basil of Caesarea and Gregory of Nazianzus are known as the Cappadocian Fathers. They attempted to establish Christian philosophy as superior to Greek philosophy.