Theseus was a Greek historian active during the Hellenistic period, with a floruit broadly placed between the 3rd century BCE and the 2nd century CE. No details of his biography, geography, or education survive.

He is credited with a single, lost work titled On the Jews. It is preserved only in a citation by Clement of Alexandria, who records that Theseus claimed the Athenian lawgiver Solon borrowed his law against idleness from the law of Moses.

Theseus is a minor but attested figure in the study of Hellenistic-Jewish intellectual relations. His fragment represents a notable assertion of Jewish cultural priority over Greek civilization, a trope employed in both Jewish apologetic and later Christian literature seeking to harmonize Greek philosophy with biblical tradition.