Demetrius was an Athenian comic poet who lived and worked in the 5th century BCE, during the Classical period. He is associated with Old Comedy, the same vibrant theatrical tradition as the famous playwright Aristophanes. Beyond this basic identification, no details of his life are known.

Ancient sources, primarily a Byzantine encyclopedia called the Suda, record that he wrote two comedies: Sicily and The Women of Laconia. Both plays are now lost, surviving only as titles. According to modern scholars, these titles are historically significant. Sicily likely engaged with contemporary Athenian military interests in Sicily, possibly referencing the disastrous Sicilian Expedition of the Peloponnesian War. The Women of Laconia, featuring a chorus of Spartan women, would also have resonated with an Athenian audience during the long conflict against Sparta.

Demetrius is considered a very minor figure, as none of his actual writing survives. His importance lies in his inclusion in ancient catalogs of dramatists, which helps historians understand the breadth of the comic theater in Athens. He represents the many lesser-known poets who, through plays on topical themes, contributed to the rich cultural and political commentary of Athenian Old Comedy.