Legio I Iovia: one of the legions of the later Roman empire. Its name means "the legion dedicated to Jupiter".
This legion was created by the emperor Diocletian (r.284-305), who was often called Iovianus, "the man like Jupiter". The date of this unit's creation has not been recorded, but was probably at the beginning of Diocletian's reign. Together with II Herculia, which seems to have been the twin of I Iovia, it was stationed in the newly created province of Scythia (near the mouth of the Danube).
It was still there when the text known as the Notitia Dignitatum (a list of magistracies and army units) was composed (c.400), and may have survived into the early Byzantine Empire.