Aristodemus of Nyssa was a Hellenistic historian of the 1st century BCE from the city of Nyssa in Caria. No details of his life, education, or social background survive.

His sole known work, the Historiai, survives only in fragments. This compilation covered events from Greek history, including the Persian Wars and figures like Themistocles. It was composed of anecdotes drawn from earlier historical traditions rather than original research.

Aristodemus is significant as a source preserving fragments of earlier historical narratives. Cited by later authors like the grammarian Charisius, his work exemplifies the Hellenistic tradition of producing epitomes and compilations. His value to modern scholarship lies in these fragments, which may contain otherwise lost variants, though he remains a minor figure in the historiography of the period.