De vita Caesarum, commonly known as The Twelve Caesars or The Lives of the Twelve Caesars, is a set of twelve biographies of Julius Caesar and the first 11 emperors of the Roman Empire during the Principate. The subjects are Julius Caesar, Augustus, Tiberius, Caligula, Claudius, Nero, Galba, Otho, Vitellius, Vespasian, Titus, and Domitian.