Imperial Cult

As the Roman Empire developed, the Imperial cult gradually developed more formally and constituted the worship of the Roman Emperor as a god. This practice began at the start of the Empire under Augustus, and became a prominent element of Roman religion.

The cult spread over the whole Empire within a few decades, more strongly in the east than in the west. Emperor Diocletian further reinforced it when he demanded the proskynesis and adopted the adjective sacrum for all things pertaining to the imperial person.

The deification of emperors was gradually abandoned after the Emperor Constantine I started supporting Christianity. However, the concept of the imperial person as "sacred" carried over, in a Christianized form, into the Byzantine Empire.

Source: [Imperial cult - Wikiwand]#Ancient_Rome