Aristocritus of Miletus was a Hellenistic historian of the 3rd century BCE. His existence and work are known solely from fragments cited by later authors. He originated from the Ionian city of Miletus in Asia Minor, but no further biographical details survive.

His only known work is the Milesiaka, a history of Miletus. The work is lost, surviving only in fragments preserved by later compilers like Athenaeus, which concern local customs, historical anecdotes, and religious practices.

Aristocritus represents the Hellenistic genre of local history, or horography. His fragments provide valuable, if limited, insight into Milesian antiquities and confirm his use as a source for Ionian local history by later Greek authors.