4th Legion may refer to:
Legio IV Macedonica founded in 48 BC Legio IV Scythica founded c. 42 BC by the general Mark Antony Legio IV Flavia Felix founded in AD 70 by the emperor Vespasian from the ashes of the Legio IV Macedonica Legio IV Martia Legio IV Italica founded in AD 231 by emperor Alexander Severus