Gorgias was a Greek teacher of rhetoric and a major figure among the Sophists, active in the 5th and early 4th centuries BCE. He was born around 483 BCE in Leontini, Sicily, and lived to an exceptionally old age, dying around 376 BCE. His career reached a turning point in 427 BCE when he traveled to Athens as an ambassador. His eloquent speeches there are considered a key moment in introducing sophisticated Sicilian rhetoric to Athenian culture. He subsequently traveled widely, teaching the art of persuasive speech for pay and amassing significant wealth and fame.

Gorgias's philosophical views were radical. In his work On Non-Being, he argued that nothing exists; that if anything did exist, it could not be known; and that if it could be known, it could not be communicated. According to modern scholars, this is often interpreted as a skeptical critique of earlier philosophy and a demonstration of rhetoric's power to argue any position.

Very few of his works survive intact. His most famous complete piece is the Encomium of Helen, a speech that defends Helen of Troy by arguing she was overcome by persuasive speech, force, fate, or love. Another surviving fragment is the Defense of Palamedes, a model courtroom speech. These works showcase the elaborate "Gorgianic style," characterized by balanced clauses, antithesis, and rhythmic patterns that heavily influenced later Greek prose.

Gorgias is a foundational figure in the history of rhetoric. His embassy is traditionally seen as sparking Athenian interest in formal oratory. His teachings emphasized the supreme power of speech (logos) to persuade and shape belief, a concept famously explored and critiqued by Plato in his dialogue Gorgias.