Aristarchus or Aristarch (Ancient Greek: Ἀρίσταρχος Aristarkhos), "a Macedonian of Thessalonica" (Acts 27:2), was an early Christian mentioned in a few passages of the New Testament.

Along with Gaius, another Roman Macedonian, Aristarchus was seized by the mob at Ephesus and taken into the theater (Acts 19:29).

Later, Aristarchus returned with Paul from Greece to Asia (Acts 20:4).

At Caesarea, he embarked with Paul on a ship of Adramyttium bound for Myra in Lycia (Acts 27:2); whether he traveled with him from there to Rome is not recorded.

He is commemorated as a saint and martyr on January 4, April 14, and September 27.