Gaius Suetonius Tranquillus [ˈɡaː.ɪ.ʊs ˈswɛ.tɔn.jʊs traŋˈkᶣɪl.lʊs], commonly known as Suetonius (/swɪˈtoʊniəs/; c. 69 – after 122 AD), was a Roman historian belonging to the equestrian order who wrote during the early Imperial era of the Roman Empire.His most important surviving work is a set of biographies of twelve successive Roman rulers, from Julius Caesar to Domitian, entitled De Vita Caesarum. He recorded the earliest accounts of Julius Caesar's epileptic seizures.