A slave of Philemon of Colossae who ran away — perhaps having robbed his master (Philemon 18) — reached Paul in prison, was converted ('whom I begot in my chains', v10), and was sent home carrying the letter that asks Philemon to receive him 'no longer as a slave but… a beloved brother' (v16). His name means 'useful, profitable', and Paul puns on it: 'once useless (achrēstos) to you, now useful (euchrēstos)' (v11). ⚠ Colossians 4:9 sends him back openly as 'the faithful and beloved brother, who is one of you', so the two letters travel together. By an early and attractive tradition the same Onesimus became bishop of Ephesus a generation later (Ignatius, c. AD 110, praises a bishop of that name and plays on the same pun) — and on a well-known modern guess it was he who gathered Paul's letters into the collection that preserved this one.