The Roman emperor was the ruler and monarchical head of state of the Roman Empire, starting with the granting of the title augustus to Octavian in 27 BC. The term "emperor" is a modern convention, and did not exist as such during the Empire. 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 used was imperator, originally a military honorific, and caesar, originally a surname. Early emperors also used the title princeps alongside other Republican titles, notably consul and pontifex maximus.
Bust of Augustus wearing the corona civica
Augustus depicted as a magistrate at the Ny Carlsberg Glyptotek
Cameo of Augustus in a quadriga drawn by tritons at the Kunsthistorisches Museum, Vienna
Denarius of Augustus (18 BC).
The Roman Empire was the post-Republican state of ancient Rome. It is generally understood to mean the period and territory ruled by the Romans following Octavian's assumption of sole rule under the Principate in 27 BC. It included territories in Europe, North Africa, and Western Asia and was ruled by emperors. The fall of the Western Roman Empire in 476 AD conventionally marks the end of classical antiquity and the beginning of the Middle Ages.
Augustus of Prima Porta
Nerva (r. 96–98)
Trajan (r. 98–117)
Hadrian (r. 117–138)