15-year-old Christian virgin who, probably during the persecution of Christians by the Roman emperor Diocletian, threw herself from a housetop to save her chastity and died instantly. Her authenticity was endorsed and praised by St. Ambrose and St. John Chrysostom who celebrated her martyrdom in a homily.

The memory of this historical Pelagia influenced two legends of fictitious Pelagias—Pelagia the Penitent (or Margarito) and Pelagia Margaret of Tarsus. Pelagia the Penitent was a prostitute of Antioch who experienced sudden conversion to Christianity and then lived her remaining life in a cave at Jerusalem, disguised as a man. Pelagia of Tarsus, for refusing to marry Diocletian, was roasted to death. Both legends are associated with that of St. Margaret of Antioch.