(Δικαίαρχος; Dikaíarchos) from Messene (in Sicily [1. 43]), student of Aristotle.
D. (born c. 375 BC?) spent a part of his life in the Peloponnese (Cic. Att. 6,2,3; fragments and testimonials in ; list of writings in ). As with other early Peripatetics, the breadth of D.'s interests is remarkable; Varro (Rust. 1,2,6) and Pliny (HN 2,162) describe him as ‘highly learned’, Cicero (Att. 6,2,3) as ‘very well instructed’ (ἱστορικώτατος).