Octavian, known to posterity as the Emperor Augustus Caesar, was the first emperor of Rome, the first of the Julio-Claudian Dynasty, the adopted son of his great-uncle Julius Caesar, and possibly the most important man in Roman history.
Octavian or Augustus lived from 63 B.C. - A.D. 14.
The date at which he began his rule could be either 31 B.C., when the forces of Augustus under Agrippa defeated those of Mark Antony and Cleopatra at the Battle of Actium, or in 27 B.C. when Octavian became Augustus, a term of honor awarded him by the Senate.
Octavian / Augustus' Achievements
Octavian / Augustus reformed the Praetorian Guard and laws on marriage and adultery, he had the power of a tribune, and was Pontifex Maximus (head priest). He extended the boundaries of the Roman Empire, caused the Pax Romana, and built up the city of Rome [see Augustus' famous saying].
Misfortunes of Augustus' Reign
Through the long years of his reign, Octavian / Augustus put an end to the already seriously decaying republican system of government. It was under his rule that Varus suffered a disastrous defeat in Teutoberg Wald, putting a temporary end to territorial ambition beyond the Rhine. His own daughter and grand-daughter defied Octavian's lofty moral stance. Although both partners were demonstrably capable of producing children, Augustus failed to produce an heir with Livia, his wife during his long term as emperor. Ultimately, Octavian / Augustus had little choice but to make his begrudging son-in-law, Livia's son Tiberius his successor, even though Tiberius wasn't much to his liking.
Augustus is quoted as saying, "If I have played my part well, clap your hands, and dismiss me with applause from the stage." See Greek and Latin Quotes for the source.