Eparchides of Oineis was a 4th-century BCE Athenian author, known only from a citation in the lexicographer Harpocration. His name identifies him as coming from the deme of Oineis, part of the Athenian tribe Oineis in northern Attica. No further biographical details survive.

His sole attested work is On the Demes of Attica, a lost prose treatise cited by Harpocration for information on Athenian civic subdivisions.

Eparchides was a minor Atthidographer, a chronicler of Attic local history and institutions. His work contributed specific details on Athenian deme organization, serving as a reference for later antiquarians, though its impact was far more limited than that of major figures in the tradition.