New Defender's Study Bible Notes
24 Marcus. Mark had once left Paul (Acts 13:13), but apparently was now back with him at Rome. Aristarchus was a Macedonian convert from Thessalonica (Acts 27:2) who later worked with Paul.
24 Demas. Demas and Luke, especially the latter, were often with Paul in his earlier ministries. Demas, however, later defected and went back into the world (II Timothy 4:10), while Luke, the beloved physician, stayed with Paul to the end (Colossians 4:14; II Timothy 4:11). Whether any of these men knew Philemon personally is not certain, but at least they wanted to join Paul in his greetings to him.