Dio Chrysostom of Prusa was a Greek orator, writer, and philosopher of the Roman Imperial period, active during the late 1st and early 2nd centuries CE. Born to a wealthy family in Prusa, Bithynia, his posthumous nickname "Chrysostom," meaning "golden-mouthed," attested to his renowned eloquence.

Exiled by Emperor Domitian, he adopted a Cynic lifestyle during his extensive wanderings, an experience that deeply shaped his philosophical thought. He later returned to imperial favor, becoming a friend and advisor to Emperor Trajan. Approximately 80 orations survive under his name.

These speeches, such as the four Orations on Kingship addressed to Trajan and the Olympic Oration, cover topics including ethics, politics, and literature. They blend Cynic and Stoic ideas in an accessible style. Dio is a major representative of the Second Sophistic, a movement that reaffirmed Greek cultural identity under Roman rule.

His works provide valuable historical insight into the political and intellectual life of the eastern Roman Empire. He was instrumental in popularizing philosophical ethics and influenced later Greek prose through his skilled revival of the classical Attic style.