Theophilus of Antioch was a Christian bishop and author who lived during the 2nd century CE in the Roman Empire. He served as the sixth bishop of Antioch, a major city in Syria, from approximately 169 CE until his death, likely around 183–185 CE. According to his own testimony, he was a convert to Christianity from paganism and had received a thorough Greek education, making him familiar with classical literature and philosophy.

His only surviving work is a three-book treatise titled To Autolycus, written to a pagan friend. It is a defense of the Christian faith that critiques pagan mythology and idolatry while arguing for Christian monotheism and ethics. The work is a valuable source for understanding how early Christians engaged with the surrounding Greco-Roman culture. Theophilus is also noted for a significant contribution to Christian theology: he is the first known author to use the Greek word "Triad" (Τριάς) to describe the Godhead, referring to God, the Word (Logos), and Wisdom (Sophia). This contributed to the development of later Trinitarian thought. Modern scholars view his writings as important evidence for how New Testament texts were used and how Genesis was interpreted by the late 2nd century.

Later church historians mention that Theophilus wrote other works, including commentaries and arguments against various heresies, but these are now lost.