Theopompus was an Athenian comic poet active in the late 5th and early 4th centuries BCE, a period known as Old Comedy. He was a contemporary and rival of the more famous Aristophanes, competing against him in Athenian dramatic festivals. Ancient records indicate he won first prize at the Lenaea festival three times, with his first victory dated to around 410 BCE.

He wrote numerous comedies, though they survive only in fragments quoted by later authors. According to a Byzantine encyclopedia, he wrote 24 plays. Known titles from the surviving fragments include Peace, Penelope, and Admetus. These works typically featured mythological parody and political satire, common elements of Old Comedy.

Modern scholars see Theopompus as a significant figure in the transition from Old Comedy to the subsequent style known as Middle Comedy. His fragments provide valuable evidence for the themes and evolution of Athenian comedy during his lifetime. While not all ancient critics praised his work—Aristotle, for example, criticized the construction of his plots—his frequent mentions by peers confirm his standing as a recognized poet of his era.