Martyr Sebastian at Rome and his companions

Sebastian was a Roman martyr who died during the Diocletianic persecution, commemorated in the Orthodox Church on December 18. He is also venerated in the Western Church on January 20, making him one of the pre-schism saints of the undivided Church whose memory is shared across traditions. His relics were buried on the Via Appia in Rome, and a basilica bearing his name has marked the site since the fourth century, attesting to an early and continuous cult. The historical details of his life rest on a hagiographic Acts compiled no earlier than the early fifth century; the Catholic Encyclopedia notes that beyond the fact of his martyrdom, very little can be confirmed from contemporary historical evidence.

According to the traditional Acts, Sebastian was born in Narbo Martius (modern Narbonne in southern France) and educated in Mediolanum (Milan). He entered the Roman army and became an officer in the imperial Praetorian Guard under Emperors Diocletian and Maximian, who did not know him to be a Christian. The Acts describe him as using his position to encourage and strengthen imprisoned Christians awaiting execution. Among those he is said to have supported were the deacons Marcellinus and Mark and their father Tranquillinus, and Tiburtius the son of the prefect Chromatius. When his Christian identity was discovered, Diocletian ordered Mauretanian archers to execute him; Sebastian was shot with arrows and left for dead, but was found alive by a woman named Irene of Rome, who nursed him back to health. He then reportedly presented himself before Diocletian to rebuke the persecution, after which he was beaten to death with clubs and his body thrown into a sewer. A Christian woman named Lucina recovered the body and buried it near the catacombs on the Via Appia, at the site where a basilica was later built.