Dieuchidas of Megara was a 4th-century BCE historian from the city of Megara. He represents the Classical tradition of local historiography, compiling his city's history from a Megarian perspective during a period of frequent rivalry with Athens.

His sole known work is the Megarika, a history of Megara in at least four books. The text is lost, surviving only in fragments preserved by later authors like Athenaeus and Clement of Alexandria. The Megarika covered foundation myths, early kings, rituals, and customs, often engaging in polemics to defend Megarian traditions against rival accounts.

Dieuchidas is significant for providing a valuable non-Athenian viewpoint on regional history and myth. His rationalizing approach to myth is notable, as seen in a fragment where Apollo aids in building Megara's walls by lending his lyre to set a work rhythm, rather than through direct divine intervention.