Roman Emperor By NumberCat Period: 27 BCE to 14 Augustus Period: 96 to 180 Pentiarchy Period: 235 to 284 Third Century Period: 284 to 330 Diocletian Period: 330 to 395 Constantine Period: 476 to 552 Barbarians Period: 552 to 797 Justinian Period: 797 to 800 Irene Period: 800 to 900 Charlemagne