Who Were the Imperial Roman Emperors?

Five emperors in the Julio-Claudian Era as depicted in stone relief.

Carole Raddato / Wikimedia Commons / CC BY 2.0

The Imperial period is the time of the Roman Empire. The first leader of the Imperial period was Augustus, who was from the Julian family of Rome. The next four emperors were all from his or his wife's (Claudian) family. The two family names are combined in the form Julio-Claudian. The Julio-Claudian era covers the first few Roman emperors: Augustus, Tiberius, Caligula, Claudius, and Nero.​

Ancient Roman history is divided into 3 periods:

  1. Regal
  2. Republican
  3. Imperial

Sometimes a fourth period is included: the Byzantine Period.

The Rules of Succession

Since the Roman Empire was new at the time of the Julio-Claudians, it still had to work out issues of succession. The first emperor, Augustus, made much of the fact that he was still following the rules of the Republic, which permitted dictators. Rome hated kings, so although emperors were kings in all but name, a direct reference to the succession of the kings would have been anathema. Instead, the Romans had to work out the rules of succession as they went.

They had models, like the aristocratic road to political office (cursus honorum), and, at least in the beginning, expected emperors to have illustrious ancestors. It soon became apparent that a potential emperor's claim to the throne required money and military backing.

Augustus Appoints a Co-Regent

The senatorial class historically passed along their status to their offspring, so succession within a family was acceptable. However, Augustus lacked a son to whom to pass along his privileges. In B.C. 23, when he thought he would die, Augustus handed a ring conveying imperial power to his trusted friend and general Agrippa. Augustus recovered. Family circumstances changed. Augustus adopted Tiberius, his wife's son, in 4 A.D. and gave him proconsular and tribunician power. He married his heir to his daughter Julia. In 13 A.D., Augustus made Tiberius co-regent. When Augustus died, Tiberius already had imperial power.

Conflicts could be minimized if the successor had the opportunity to co-rule.

Tiberius' Two Heirs

Following Augustus, the next four emperors of Rome were all related to Augustus or his wife Livia. They are referred to as Julio-Claudians. Augustus had been very popular and Rome felt allegiance to his descendants, too.

Tiberius, who had been married to Augustus' daughter and was the son of Augustus' third wife Julia, had not yet openly decided who would follow him when he died in 37 A.D. There were two possibilities: Tiberius' grandson Tiberius Gemellus or the son of Germanicus. On Augustus' order, Tiberius adopted Augustus' nephew Germanicus and named them equal heirs.

Caligula's Illness

The Praetorian Prefect, Macro, supported Caligula (Gaius) and the Senate of Rome accepted the prefect's candidate. The young emperor seemed promising at first but soon suffered a serious illness, from which he emerged a terror. Caligula demanded extreme honors to be paid to him and otherwise humiliated the Senate. He alienated the praetorians who killed him after four years as emperor. Unsurprisingly, Caligula had not yet selected a successor.

Claudius is Persuaded to Take the Throne

Praetorians found Claudius cowering behind a curtain after they assassinated his nephew Caligula. They were in the process of ransacking the palace, but instead of killing Claudius, they recognized him as the brother of their much loved Germanicus and persuaded Claudius to take the throne. The Senate had been at work finding a new successor, but the praetorians again imposed their will.

The new emperor bought the continued allegiance of the praetorian guard.

One of Claudius' wives, Messalina, had produced an heir known as Britannicus, but Claudius' last wife, Agrippina, persuaded Claudius to adopt her son — whom we know as Nero — as heir.

Nero, the Last of the Julio-Claudian Emperors

Claudius died before the full inheritance had been accomplished, but Agrippina had support for her son, Nero, from the Praetorian Prefect Burrus — whose troops were assured a financial bounty. The Senate again confirmed the praetorian's choice of successor, and so Nero became the last of the Julio-Claudian emperors.

Later Successions

Later emperors often designated successors or co-regents. They could also bestow the title of "Caesar" on their sons or another family member. When there was a gap in the dynastic rule, the new emperor had to be proclaimed either by the Senate or the army, but the consent of the other was required to make the succession legitimate. The emperor also had to be acclaimed by the people.

Women were potential successors, but the first woman to rule in her own name, Empress Irene (c. 752 - August 9, 803), and alone, was after the Julio-Claudian time period.

Succession Problems

The first century saw 13 emperors. The second saw nine, but the third produced 37 (plus the 50 that never made it to the rolls of the historians). Generals would march on Rome, where the terrified senate would declare them emperor (imperator, princeps, and augustus). Many of these emperors ascended with nothing more than force legitimating their positions and had assassination to look forward to.


Burger, Michael. "The Shaping of Western Civilization: From Antiquity to the Enlightenment." 1st Edition, University of Toronto Press, Higher Education Division, April 1, 2008.

Cary, H.H. Scullard M. "A History of Rome." Paperback, Bedford/St. Martin's, 1976.

"Memoirs of the American Academy in Rome." Vol. 24, University of Michigan Press, JSTOR, 1956.

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Gill, N.S. "Who Were the Imperial Roman Emperors?" ThoughtCo, Feb. 16, 2021, thoughtco.com/roman-imperial-succession-julio-claudian-era-120625. Gill, N.S. (2021, February 16). Who Were the Imperial Roman Emperors? Retrieved from https://www.thoughtco.com/roman-imperial-succession-julio-claudian-era-120625 Gill, N.S. "Who Were the Imperial Roman Emperors?" ThoughtCo. https://www.thoughtco.com/roman-imperial-succession-julio-claudian-era-120625 (accessed June 2, 2023).