Aphthonius of Antioch was a Greek teacher of rhetoric, or sophist, who lived and worked in the late 4th century CE. He came from Syria and was a student of the famous orator Libanius in the city of Antioch. As a sophist, his profession involved teaching the art of public speaking and composing formal speeches for display. This was a common career for educated elites in the late Roman Empire, though the specific details of his public life are not recorded.

His lasting importance comes from a single surviving work: a textbook called the Progymnasmata. This book outlines fourteen standard preliminary exercises used to train students in rhetoric, such as writing fables, narratives, and short arguments. According to modern scholars, its clear organization and practical examples made it an exceptionally influential teaching tool. It became a fundamental textbook for centuries, used throughout the Byzantine period and into early modern Europe to teach the foundational skills of composition and argument. Through this manual, Aphthonius played a key role in transmitting the techniques of classical Greek rhetoric to later generations. His work is often studied alongside similar handbooks by other ancient rhetoricians as a crucial part of the educational tradition.