Istros the Callimachean (in Greek Ἴστρος ὁ Καλλιμάχειος) was a Greek writer pupil of Callimachus and active in the Library of Alexandria.
The Suda affirms that Istros wrote extensively in both prose and verse. His works exist only in fragments (FGrHist 334). Among his attested works are:
Attika (Ἀττικά)Atakta (Ἄτακτα)Attikai lexeis (Ἀττικαὶ λέξεις)Argolika (Ἀργολικά)Eliaka (Ἠλιακά)The colonies of the Egyptians (Αἰγυπτίων ἀποικίαι)On the city of Ptolemais (Περὶ Πτολεμαΐδος)Collection of Cretan feasts (Συναγωγὴ τῶν Κρητικῶν θυσιῶν)On the struggles of Helios (Περὶ τῶν Ἡλίου ἀγώνων)The manifestations of Apollo (Ἀπόλλωνος ἐπιφάνειαι)The manifestations of Hercules (Ἡρακλέους ἐπιφάνειαι)On the lyric poets (Περὶ μελοποιῶν)Symmikta (Σύμμικτα)Hypomnemata (Ὑπομνήματα)Replies to Timeus (Πρὸς Τίμαιον ἀντιγραφαί)