Agathon was an Athenian tragic poet of the late 5th century BCE. He is a well-attested historical figure, celebrated for his first victory at the Lenaea festival in 416 BCE, an event dramatized in Plato's Symposium where he appears as a character. Aristophanes parodied his ornate style and luxurious lifestyle in comedies like Thesmophoriazusae and Frogs.

According to Aristotle, Agathon was innovative, being the first to compose choral odes detachable from the plot and to write a tragedy with entirely fictional characters. He later left Athens for the court of King Archelaus of Macedon, where he died.

His works are almost entirely lost, surviving only in fragments and titles. Ancient sources attribute several plays to him, including Thyestes, Aerope, Telephus, Antheus, Alcmaeon, and Mysians. A single fragment of seven lines, possibly from Thyestes, is preserved by Aristotle.

Agathon was a significant innovator in later Greek tragedy. His move toward invented plots and detachable choral songs marked a shift from traditional mythic cycles. His celebrity in Athenian intellectual circles and his distinctive, florid literary style, which influenced later rhetoric, made him a symbol of the sophisticated modern artist.