Augustus (Latin: IMP•CAESAR•DIVI•F•AVGVSTVS; September 23, 63 BC–August 19, AD 14), known as Gaius Julius Caesar Octavianus (English Octavian; Latin: C•IVLIVS•C•F•CAESAR•OCTAVIANVS) for the period of his life prior to 27 BC, was the first and among the most important of the Roman Emperors. In 42 BC, Caesar was formally deified as Divus Iulius ("the Divine Julius"), and Caesar Augustus henceforth became Divi filius ("Son of a god").

Although he preserved the outward form of the Roman Republic, he ruled as an autocrat for 41 years, longer than any subsequent Emperor; and his rule is the dividing line between the Republic and the Roman Empire. He is regarded as one of the most influential figures in World History. He ended a century of civil wars and gave Rome an era of peace, prosperity, and imperial greatness, known as the Pax Romana, or Roman peace, which lasted for over 200 years.