The roll of emperors spans more than 500 years of Roman history. All of those listed bore the title; a dozen of the most famous are noted with an *. The list has been simplified by excluding certain usurpers, claimants and co-emperors of relatively little importance. The length of the emperors' reigns varied enormously. The Golden Age of Augustus lasted 41 years, and Theodosius II served for 42 years; but in the troubled years 68-69, Galba, Otho and Vitellius averaged less than six months on the throne. By the end of the Fourth Century, during the reign of Honorius, the Empire had been permanently divided, with separate rulers for the West, in Rome, and for the East (E), in Constantinople.