Tatian (c. AD 120–180) was an early Christian apologist and disciple of Justin Martyr whose writings provide a valuable witness to the faith of the second-century Church. Born in the region of Assyria, Tatian travelled widely before embracing Christianity and studying under Justin in Rome, where he became a defender of the Gospel against the pagan philosophies and moral criticisms of his age. His most famous work, the Oration to the Greeks (Oratio ad Graecos), challenged the claims of Greek culture and philosophy while proclaiming the supremacy of the one God revealed in Christ. He is also remembered for composing the Diatessaron, a harmony of the four canonical Gospels that became one of the earliest attempts to present the life of Jesus in a unified narrative and was widely used among Syriac-speaking Christians for centuries. Though Tatian's later association with the ascetic Encratite movement led some Church Fathers to question aspects of his teaching, his earlier writings remain a significant testimony to the spread of Christianity, the authority of the apostolic Scriptures, and the intellectual defence of the faith in the ancient world.