St Issac the Syrian (also known as Isaac of Nineveh) was a seventh century monk and mystic. Like many pre-Schism saints, he is also revered by the Roman and Eastern-rite Catholic Churches. He was born on the Arabian Peninsula, near present-day Qatar.
A strict ascetic, the saint entered monastic life at a young age along with his brother, and studied the Scriptures in isolation for many years. Eventually elevated as bishop of the ancient Assyrian capital of Nineveh, he abdicated this role after five months to return to the desert. He reposed around the year 700.
Holy Father Isaac, pray to God for us!