Saint Basil (circa 329-379), called Basil the Great, Father and Doctor of the Church, patriarch of Eastern monasticism.

Born of wealthy parents in Caesarea Mazaca (modern Kayseri, Turkey), Basil was educated in Athens and Constantinople (present-day İstanbul). After visiting a number of noted hermits in Egypt and Syria, he gave up an administrative career and settled as a hermit by the river Iris in Neo-Caesarea. There he wrote much of a monastic rule of life that became the basis for an order of monks (later called Basilian monks) that he founded about 360. Most Orthodox and some Roman Catholic monks still follow the rule of St. Basil. Noted for his brilliance and the holiness of his life, he was called upon by the bishop of Caesarea to defend Christian doctrine against the heretical attacks of the Arians (see Arianism). In 370 he himself was elected bishop of Caesarea, a post he held until his death on January 1, 379.

His writings include Against Eunomius, three books directed against the Arian leader Eunomius; On the Holy Spirit, a doctrinal treatise; and the Moralia, an anthology of New Testament verses. He also wrote a liturgy (known as the Liturgy of St. Basil) still used in the Byzantine rite. His feast day is January 1 in the Eastern church and January 2 in the Western church.

Basil, his brother St. Gregory of Nyssa, and his friend St. Gregory of Nazianzus are known collectively as the Cappadocian Fathers. Basil's grandmother Macrina; his parents, Basil and Emmelia; his sister Macrina, and his younger brothers Gregory and Peter of Sebaste are all venerated as saints.