Demetrius of Phaleron was an Athenian orator, statesman, and philosopher who lived from approximately 350 to 280 BCE. A student of Theophrastus, he belonged to the Peripatetic school of philosophy founded by Aristotle. Following Athens's defeat by Macedon, he was appointed governor of the city with Macedonian support, ruling from 317 to 307 BCE. His moderate oligarchic rule ended when he was forced into exile. He eventually found refuge in Alexandria at the court of Ptolemy I Soter.

Ancient sources record that Demetrius was a prolific writer on history, rhetoric, philosophy, and literary criticism, but his works survive only in fragments. A famous treatise On Style was long attributed to him, but modern scholars generally believe it was written by a later, unknown author. His genuine, fragmentary writings include histories, political works, and collections of fables.

Demetrius is a significant transitional figure between the Classical and Hellenistic periods. His decade in power marked the end of Athenian political autonomy. According to many scholars, his intellectual legacy is tied to the early planning of the Library of Alexandria, where he is traditionally credited with an advisory role, linking him to one of the ancient world's greatest centers of learning. His fragmentary works later influenced historians, rhetoricians, and compilers of anecdotes.