Agathocles of Cyzicus (Ἀγαθοκλῆς ὁ Κυζικηνός) was a Hellenistic historian of the 3rd century BCE, a native of the city of Cyzicus on the Sea of Marmara [1]. Beyond this origin and the titles of his works, no specific biographical details survive.

Two fragmentary works are attributed to him, both known only from later citations. According to the Suda, he authored On Cyzicus (Περὶ Κυζίκου), a local history of his city, and On the Propontis (Περὶ Προποντίδος), concerning the geography and history of the surrounding region [1]. These prose works, written in the Ionic dialect, are preserved only in fragments quoted by authors like Athenaeus [1].

Agathocles represents the Hellenistic tradition of local history and chorography. His writings provided later geographers and commentators with valuable antiquarian, mythological, and geographical information, contributing to the scholarly knowledge of local cults and foundations characteristic of the period [1].

Sources 1. Encyclopædia Britannica: https://www.britannica.com/biography/Agathocles-of-Cyzicus 2. Perseus Digital Library, Suda entry for Agathocles: https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Da%29gqoklh%3Ds2