 Justinian I ( / <unk> / ; Latin : Flavius Petrus <unk> Iustinianus Augustus , Greek : Φλάβιος <unk> <unk> <unk> <unk> <unk> <unk> <unk> ) ( c . 482 – 14 November 565 ) , traditionally known as Justinian the Great and also Saint Justinian the Great in the Eastern Orthodox Church , was a Byzantine ( East Roman ) emperor from 527 to 565 . During his reign , Justinian sought to revive the empire 's greatness and reconquer the lost western half of the historical Roman Empire . Justinian 's rule constitutes a distinct epoch in the history of the Later Roman empire , and his reign is marked by the ambitious but only partly realized <unk> imperii , or " restoration of the Empire " . 
