Gaius Suetonius Tranquillus (c. 69/75 - after 130), also known as Suetonius, was a prominent Roman historian and biographer.
He was the son of Suetonius Laetus, who probably came from Hippo Regius (Annaba, Algeria). Laetus was an equestrian who served as a regular colonel and took part in the first Battle of Bedriacum for the Emperor Otho and against the future Emperor Vitellius in 69.
Suetonius was a close friend to Senator and historian Pliny the Younger. Pliny describes him as quiet and studious, a man dedicated to writing. Pliny helped him buy a small property in Italy and interceded with the Emperor Trajan to grant Suetonius immunities usually granted to a father of three, the jus trium liberorum, even though Suetonius never married or had any children. Through Pliny, Suetonius came into favor with Trajan and Hadrian.
Suetonius served on Pliny’s staff when Pliny was Proconsul of Bithynia Pontus (northern Asia Minor) between 110 and 112. Under Trajan he served as secretary of studies (precise functions are uncertain) and director of Imperial archives. Under Hadrian, he became the Emperor's secretary.
In 122, Hadrian dismissed him for disrespectful behaviour towards Empress Vibia Sabina. Suetonius may have later regained imperial favor under Hadrian and returned to his position. This hypothesis is based on the suggestion that Offices of State was one of his last works, and that the subject was chosen to reflect Hadrian's administrative reforms. However, there is no certain evidence for a public career after 122.
He is mainly remembered as the author of De Vita Caesarum ("Lives of the Caesars", best known in English as "The Twelve Caesars"), his only extant work except for the brief lives and other fragments noted below. The Twelve Caesars, probably written in Hadrian's time, is a collective biography of the Roman Empire's first leaders who were: Julius Caesar (the first few chapters are missing), Augustus, Tiberius, Caligula, Claudius, Nero, Galba, Otho, Vitellius, Vespasian, Titus and Domitian. The book was dedicated to a friend Gaius Septicius Clarus, a prefect of the Praetorian Guard in 119. The work tells the tale of each Caesar's life according to a set formula: the descriptions of appearance, omens, family history, quotes, and then a history are given in a consistent order for each Caesar. Suetonius regarded emperors who amassed wealth for the public purse to be "greedy", perhaps a reflection of the average Roman middle class attitudes.
The two last works were written in Greek. They apparently survive in part in the form of extracts in later Greek glossaries.