(Ἀγάθαρχος), a Syracusan, who was placed by the Syracusans over a fleet of twelve ships in B. C. 413, to visit their allies and harass the Athenians. He was afterwards, in the same year, one of the Syracusan commanders in the decisive battle fought in the harbour of Syracuse. (Thuc. 7.25, 70; Diod. 13.13.)