Legio V Iovia: one of the legions of the later Roman empire. Its name means "the legion dedicated to Jupiter".
This unit was created by the emperor Diocletian (284-305), who was often called Iovianus, "the man like Jupiter". The date of the legion's creation is unknown, but was probably at the beginning of his reign.
Together with IIII Flavia Felix (in Singidunum) and VI Herculia (at Teutoburgium), V Iovia protected the important city Sirmium (Sremska Mitrovica). It must have stayed at Castellum Onagrinum on the north bank of the Danube. Together, V Iovia and VI Herculia were the garrison of the newly created province of Pannonia Secunda.
It was still at Castellum Onagrinum when the text known as the Notitia Dignitatum (a list of magistracies and army units) was composed (c.400).