The Roman emperor was the ruler of the Roman Empire during the imperial period (starting with the granting of the title augustus to Octavian 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 (and later basileus). Another title often used was caesar, used for heirs-apparent, and imperator, originally a military honorific. Early emperors also used the title princeps civitatis ("first citizen"). Emperors frequently amassed republican titles, notably princeps senatus, consul, and pontifex maximus.