Pope Leo III

Pope Leo III (Latin: Leo III; died 12 June 816) was bishop of Rome and leader of the Papal States from 26 December 795 to his death on 12 June 816.

Protected by Charlemagne from the supporters of his predecessor, Adrian I, Leo subsequently strengthened Charlemagne's position by crowning him emperor. The coronation was not approved by most people in Constantinople, although the Byzantines, occupied with their own defenses, were in no position to offer much opposition.

Source: Wikipedia — https://en.wikipedia.org/wiki/Pope_Leo_III