Hermogenes of Tarsus was a Greek teacher of rhetoric who lived during the 2nd century CE, a period of renewed Greek cultural activity under Roman rule known as the Second Sophistic. Ancient sources record that he was a celebrated child prodigy, declaiming before the emperor Marcus Aurelius as a teenager. According to these accounts, his brilliant career as a performer ended prematurely due to a sudden loss of his ability while still a young man. He reportedly lived on for many years afterward, shifting his focus from performance to teaching and writing.

His lasting importance comes not from speeches, but from a series of influential technical handbooks on rhetoric written in Greek. His core surviving works include systematic treatises On Issues, concerning the bases of legal argument, On Invention, and his most famous work, On Ideas, which analyzes different styles of discourse. Another work, Progymnasmata (Preliminary Exercises), was attributed to him in later tradition, but modern scholars generally believe it was written by a different, later author.

Hermogenes is a seminal figure in the history of rhetoric. According to modern scholars, his works provided a comprehensive and systematic textbook for advanced study. His system for analyzing styles became a standard part of the curriculum. His impact as a theorist was profound, forming the foundation of rhetorical education in the Byzantine Empire for nearly a millennium, and his works were later studied in Renaissance Europe.