Romulus Augustus, nicknamed Augustulus, was Roman emperor of the West from 31 October 475 until 4 September 476. Romulus was placed on the imperial throne while still a minor by his father Orestes, the magister militum, for whom he served as little more than a figurehead. After a rule of ten months, the barbarian general Odoacer defeated and killed Orestes and deposed Romulus. As Odoacer did not proclaim any successor, Romulus is typically regarded as the last Western Roman emperor, his deposition marking the end of the Western Roman Empire as a political entity. The deposition of Romulus Augustulus is also sometimes used by historians to mark the transition from antiquity to the medieval period.

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.