Roman emperor

The Roman emperor was the ruler of the Roman State during the imperial period (starting in 27 BC). The emperors used a variety of different titles throughout history. Often when a given Roman is described as becoming "emperor" in English, it reflects his taking of the title augustus or caesar. Another title often used was imperator, originally a military honorific. Early Emperors also used the title princeps. Emperors frequently amassed Republican titles, notably princeps Senatus, consul and Pontifex Maximus.

The legitimacy of an emperor's rule depended on his control of the army and recognition by the Senate; an emperor would normally be proclaimed by his troops, or invested with imperial titles by the Senate, or both. The first emperors reigned alone; later emperors would sometimes rule with co-Emperors and divide administration of the Empire between them.

The Romans considered the office of emperor to be distinct to that of a king. The first emperor, Augustus, resolutely refused recognition as a monarch. Although Augustus could claim that his power was authentically Republican, his successor, Tiberius, could not convincingly make the same claim. Nonetheless, for the first three hundred years of Roman Emperors, from Augustus until Diocletian, a great effort was made to emphasize that the Emperors were the leaders of a Republic.