Marcus, Aristarchus, etc. - These were all acquaintances of Philemon, and probably Colossians; and may be all considered as joining here with St. Paul in his request for Onesimus. Some think that Marcus was either the evangelist, or John Mark, the nephew of Barnabas, Acts 12:12, Acts 12:25. Aristarchus was probably the same with him mentioned Acts 19:29; Acts 20:4; Acts 27:2. See Colossians 4:10.
Demas - Is supposed to be the same who continued in his attachment to Paul till his last imprisonment at Rome; after which he left him for what is supposed to have been the love of the world, but see the note on 2 Timothy 4:10.
Lucas - Is supposed to be Luke the evangelist, and author of the Acts of the Apostles. On these suppositions little confidence can be placed: they may be correct; they may be otherwise.