Tyrannius Rufinus, also called Rufinus of Aquileia (Rufinus Aquileiensis; 340/345–410), was a monk, historian, and theologian. He is most known as a translator of Greek patristic material into Latin — especially the work of Origen.
Rufinus was born in 344 or 345 in the Roman city of Julia Concordia (now Concordia Sagittaria), near Aquileia (in modern-day Italy) at the head of the Adriatic Sea. It appears that both of his parents were Christians.
Around 370, he was living in a monastic community in Aquileia when he met Jerome. In about 372, Rufinus travelled to the eastern Mediterranean, where he studied in Alexandria under Didymus the Blind for some time, and also cultivated friendly relations with Macarius the elder and other ascetics in the desert. In Egypt, if not even before leaving Italy, he had become intimately acquainted with Melania the Elder, a wealthy and devout Roman widow. When she removed to Palestine, taking with her a number of clergy and monks on whom the persecutions of the Arian Valens had borne heavily, Rufinus followed her, moving to Jerusalem in 380. There, while his patroness lived in a convent of her own in Jerusalem, Rufinus, at her expense, gathered together a number of monks to form a new monastery on the Mount of Olives, devoting himself at the same time to the study of Greek theology. This combination of the contemplative life and the life of learning had already developed in the Egyptian monasteries. When Jerome came to Bethlehem in 386, the friendship formed at Aquileia was renewed. Jerome, along with his patroness Paula, set up a similar community in Bethlehem a few years later. Another of the intimates of Rufinus was John II, Bishop of Jerusalem, and formerly a monk of the Natrun desert, by whom he was ordained to the priesthood in 390.