Tranquillus, G. Suetonius: - Gaius Suetonius Tranquillus (c. 69-after 122 CE) was a Roman historian and biographer best known for his work De Vita Caesarum (The Lives of the Twelve Caesars). Born during the early years of the Roman Empire, Suetonius served in several administrative roles under the emperors Trajan and Hadrian.His position within the imperial administration gave him access to official documents and historical records, which he used in composing detailed biographies of Julius Caesar and the first eleven Roman emperors. Rather than presenting a strictly chronological history, Suetonius organized his biographies around the character, habits, and personal conduct of each ruler.The Lives of the Twelve Caesars remains one of the most influential sources for the history of early imperial Rome and continues to shape modern understanding of the personalities who ruled the Roman world.