Romulus Augustus was the last of the Western Roman Emperors. On September 4, 476 he was compelled to abdicate by Odoacer, an act that was long considered the end of the western Roman Empire (the east continued as the Byzantine Empire until as late as 1453). By that time, though, Rome had already lost its hegemony over the provinces, and Germanic generals like Odoacer had long been the real power behind the throne.
He is frequently known by a diminutive nickname "Romulus Augustulus." The Latin termination -ulus diminishes the scale of any noun; hence, "Augustulus" would mean "the Little Augustus." However, his name was Romulus Augustus.