- Sep 10 Alonso Pérez de Guzmán, 7th Duke of Medina Sidonia, Spanish Armada commander, born in Sanlúcar de Barrameda, Cádiz, Spain (d. 1615)
- Sep 17 Pope Paul V [Camillo Borghese], 233rd pope (1605-21) and persecutor of Galileo, born in Rome (d. 1621)
- Sep 30 Michael Maestlin, German mathematician (d. 1631)