Onesimus

Onesimus (meaning profitable or useful) was a slave who had run away from his master Philemon, a wealthy Christian in Colossae, and eventually came into contact with the imprisoned Paul — possibly in Rome or Ephesus. Under Paul's ministry Onesimus became a Christian (Philemon 10) and proved so useful that Paul was tempted to keep him as an assistant. Instead, Paul sent him back to Philemon with the short letter that bears Philemon's name, appealing to Philemon to receive Onesimus no longer as a slave, but better than a slave, as a dear brother (Philemon 16), and offering to repay anything Onesimus owed.

Colossians 4:9 identifies Onesimus as a faithful and dear brother, traveling with Tychicus to Colossae. The letter to Philemon is the New Testament's most sustained engagement with the institution of slavery, demonstrating how the gospel's logic of brotherhood and mutual obligation worked within and against the social structures of the Roman world. A second-century bishop of Ephesus named Onesimus, mentioned by Ignatius, may or may not be the same person.