Aristarchus in Fausset's Bible Dictionary

Aristarchus: of Thessalonica. Paul's companion on his third missionary tour, and dragged into the theater with Gains by the mob at Ephesus; he accompanied Paul to Asia, afterward to Rome (Acts 19:29; Acts 20:4; Acts 27:2). Paul calls him "my fellow prisoner" (lit. fellow captive, namely, in the Christian warfare), "my fellow laborer," in his epistles from Rome (Colossians 4:10; Philemon 1:24). Epaphras similarly (Philemon 1:23; Colossians 1:7) is called "my fellow prisoner," "our fellow servant." Paul's two friends possibly shared his imprisonment by turns, Aristarchus being his fellow prisoner when he wrote to the Colossians, Epaphras when he wrote to Philemon. Bishop of Apamaea, according to tradition.