Augustus Caesar, Roman emperor (31 BC - AD 14)
Octavian, as Augustus was known before becoming emperor, was adopted by Julius Caesar as his son and heir and fought to avenge Caesar after his assassination in 44 BC. After the defeat of Antony and Cleopatra at the Battle of Actium in 31 BC, Augustus became undisputed master of Rome and its territories. However, his official assumption of supreme power took over two decades and he was always careful to collaborate (or at least appear to collaborate) with the senate. He was nonetheless the first true Roman emperor, an office that was to last in the Western Empire for over four hundred years. His reign gave the Roman world a much needed period of internal stability, though the Empire's boundaries continued to expand.
By the end of Augustus' reign it was clear that the Republic would not return soon if at all, and that the imperial system with its succession by birth, rather than by the will of the Senate, was firmly established. However, the question of who would succeed Augustus remained a problem, as all his chosen successors died before him, including his trusted deputy Agrippa and his grandsons Gaius and Lucius. Finally he adopted as his son and heir Tiberius, the son of his second wife Livia, who succeeded him in AD 14. Augustus was buried in a round mausoleum at the entrance to which were inscribed in bronze the Res Gestae, or achievements of his reign.