This page cannot be viewed in frames

Go to page

If you have found a spelling error, please, notify us by selecting that text and pressing Ctrl+Enter.


(20 BCE - 18 October 31 CE)

This post is also available in: Polish (polski)

A Roman Ace representing Tiberius, minted in CE 31, in Augusta Bilbilis. On the reverse there is an inscription: Augusta Bilbilis Ti(berius) Caesare L(ucius) Aelio Seiano, celebrating the Consulate of Sejanus this year.

Sejanus was born in 20 BCE in Volsinia (Etruria) as Lucius Aelius Seianus in the Seii family. Sejanus was an ambitious soldier, friend and confidant of Emperor Tiberius; Almighty Prefect of the Praetorian Guard from 14 CE. During the reign of Tiberius, he played a large role in the political life of the state.

Sejanus was the son of Lucius Sejus Strabo, an equite who became praetorian prefect under Octavian Augustus. Sejanus’ grandfather had contact with senatorial families because of his marriage to Terentia, the sister of the wife of Gaius Cilnius, who was one of the closest associates of Emperor Augustus. Sejanus’ father Strabo, like his ancestor, also established close relations with important Roman families. He probably married the daughter of Quintus Elius Tuberon, thus joining the prestigious lineage (gens) of the Elius (Aelia). Lucius Sejus Tuberon, who became consul in 18 CE, was probably his son. The last wife of Strabo was Cosconia Gallita, sister of Servius Cornelius Lentulus Maluginensis (consul for 10 CE) and Publius Cornelius Lentulus Scipio (consul for CE 2) and possibly a half-sister of Quintus Junius Blaesus (consul for CE CE). Sejanus may have come from his father’s relationship with Cosconia Gallita. Sejanus was later adopted into gens Aelia by Gaius Elius Gallus, and according to Roman custom, he was given a typical family name – Lucius Elius Sejanus.

It is believed that Sejanus’ father – Strabo – caught the attention of Emperor Augustus, due to the connection of his ancestor with the Patron. Finally, after 2 BCE, Strabo was appointed prefect of the Praetorian Guard (praefectus praetorio), achieving one of the two highest positions that a Roman equestrian could have achieved in the empire. He held his position dutifully and without errors until Augustus’ death in 14 CE.

Little is known about Sejan’s early life up to that time. According to Tacitus, he accompanied Gaius Julius Caesar, Augustus’ adopted grandson, in a military campaign in Armenia in 1 CE. After Tiberius took power in 14 CE, Sejanus assumed the position of prefectus of praetorians as the father’s companion.

The Praetorian Guard was an elite unit created by Augustus in 27 BCE to protect the emperor and his immediate family. In addition, the praetorians were responsible for ensuring the safety of the city and supporting the work of the civil administration. On the other hand, this unit was of psychological importance. It was the foundation of the empire and served as the emperor’s personal tool of influence and possible intimidation of the initiators of the plot. Initially, Augustus established the size of the unit at nine cohorts (less than in the Roman legion), which were located in different parts of the city and managed by two prefects.

When Strabo was appointed governor of Egypt in 15 CE, Sejanus took over the reign of his own. He immediately undertook the reform of the formation and established it as a powerful tool in the principate era. In 20 CE, he moved all the scattered garrisons to a single barracks, outside Rome. In addition, he increased the number of cohorts from nine to twelve, one of which was on permanent duty in the palace. The divisibility of the prefect’s office was abandoned – there was to be one commander of the Praetorian Guard from now on – and his powers were increased: he now personally appointed centurions and tribunes. Through these changes, Sejanus took full authority over a unit of approximately 12,000 soldiers that was ready to obey any order. During the reign of Emperor Tiberius, the strength of the guard was often presented at all kinds of parades, which only emphasized the end of the republic’s façade.

Rivalry with Druzus the Younger

Drusus the Younger was poisoned in 23 CE by agents of Sejanus. His wife – Claudia Julia Livilla participated in the whole plot.
Creative Commons Attribution license - On the same terms 3.0.

After making these reforms, Sejanus became a trusted and strong adviser to the emperor himself. By 23 CE, he had a significant influence on Tiberius’ decisions, who called him “Socius Laborum” (“my partner in my hardships”). During this time, Sejanus was given a praetor position, which was not normally intended for equites. A monument was built in his honour in the Pompey Theater, and with time his supporters, performing public and managerial functions, sat in the Senate. The growing power of Sejanus and his important position in the state gradually began to arouse outrage among members of the imperial family and senators. The most hostile, however, was Druzus Julius Caesar, son of Tiberius, known as Drusus the Younger.

The history of hostility between Sejanus and Druzus dates back to 15 CE when the legions stationed in Pannonia and Germania revolted imperial power. When Tiberius’ adopted son, Germanicus, calmed the revolt in Germania, Druzus the Younger was sent to Pannonia along with Sejanus and two Praetorian cohorts. Druzus quickly suppressed the rebellion and ordered the execution of the leaders of the rebellion. The camp was cleared of rebels by the praetorians, and the legion returned to their winter barracks. Despite their success, the hostility between Druzus and Sejanus grew markedly.

From the accession of Tiberius to the Roman throne, his son Druzus was seen as a very likely successor. He was victorious at the head of his legions in the Illyricum province in 18 CE, and served as consul with his father in CE 21. In practice, however, Sejanus was still the second person in the country, who still wanted to increase his power. As early as 20 CE, Sejanus, wanting to consolidate his relationship with the royal family, betrothed his 4-year-old daughter Junilla to the son of the future Emperor Claudius – Drusus IV (Claudius Drusus). Ultimately, however, they did not get married due to the fact that a few days later Claudius Druzus died of asphyxia.

It seems that the unsuccessful attempt to link with the imperial family-directed all of Sejanus’ attention to an attempt to eliminate a possible heir to the throne – Druzus. In 23 CE, the conflict between Sejanus and the son of Tiberius reached its peak. During the quarrel, Drusus punched the prefect, and openly lamented that a person outside the family had been invited to co-rule while the emperor’s son was still alive. By this time Tiberius had turned 60, and it was likely that his son Druzus would succeed him. Sejanus began to conspire and secretly persuaded Livilla, Druzus’ wife, to participate in the plot. With her help, Sejanus poisoned the heir to the throne, who was dying slowly in what appeared to be a natural death. Drusus died on September 13, 23 CE

Power Consolidation

The death of his son was a huge shock for Tiberius for personal and political reasons. The emperor deliberately relinquished many public functions to Druzus in order to prepare him for the role of emperor. The devastated Tiberius left most of the administrative duties to Sejanus and began to look for a worthy successor. It seemed that the three candidates had the best chance (sons of the deceased Germanicus): Claudius Nero Julius Caesar, Caligula and Drusus III. All three men were a threat to Sejan’s plans.

Meanwhile, Sejanus, eager to re-join the Julio-Claudian dynasty, demanded to marry Livilla in 25 CE. It was possible because Livilla was a widow of Druzus, and Sejanus had divorced his wife Apikita two years earlier. Sejanus was ready to take the name of Julian so that he could be recognized as the heir to the Roman throne. Emperor Tiberius did not agree to the request of his subordinate, arguing that he would therefore exceed his powers. Sejanus decided to change his plans and decided to isolate Tiberius from Rome. He began to spread rumours of the hatred of Agrippina the Elder (widow of Germanicus) and the Senate towards him. The paranoid emperor retired to a country estate in Campania and then to the island of Capri in 26 CE, where he spent his remaining years of life (he died in 37 CE). During Tiberius’ stay outside Rome, Sejanus easily controlled all correspondence between the emperor and the capital.

Until 29 CE, Livia (Tiberius’ mother) controlled the independent actions of Sejanus. With her death, Rome became obsessed with the period of sentences, confiscation of property, and the elimination of Sejanus’ political opponents. The prefectus eliminated the prominent senator Gaius Asinius Gallus Saloninus, an opponent of Tiberius, linked to Agrippina the Terrible faction. The widow of Germanicus, along with her sons Nero and Drusus, was forced to go into exile in 30 CE, where they all mysteriously died of starvation. Only Caligula, who had moved with Tiberius to the island of Capri, survived the persecution.


In 31 CE, despite his Equestrian origin, Sejanus shared a consulate with Tiberius in the form of in absentia (“substitutions”) and became engaged to Livilla. Tiberius, who withdrew from Rome, still formally ruled, but the actual power was exercised by Sejanus in Rome. His birthday was publicly celebrated, statues were erected and he was honoured. Sejanus believed that, once all opposition was removed, his position was unchallenged. Sejanus finally made the decision to prepare a coup d’etat, hoping to gain undivided power for himself. Warned in time by Antonia the Younger, Tiberius with the help of Macron led to the arrest of Sejanus on October 18, 31 CE and asphyxiation at the request of the Senate. After Sejanus was executed, Quintus Sutorius Makron succeeded him as Praetorian Prefect.

Sejanus’ fall also marked an end for many of his friends and supporters. His three children were also killed and his divorced wife Apicata committed suicide. It is worth mentioning here the extremely tragic death of one of his daughters Junilla, mentioned by Cassius Dio and Tacitus. As there was no precedent for the execution of a virgin to avoid the wrath of the gods, the executioner first raped the daughter of Sejanus and then strangled her.

IMPERIUM ROMANUM needs your support!

If you like the content that I collect on the website and that I share on social media channels I will be grateful for the support. Even the smallest amounts will allow me to pay for further corrections, improvements on the site and pay the server.



Find out more!

Check your curiosity and learn something new about the ancient world of the Romans. By clicking on the link below, you will be redirected to a random entry.

Random curiosity

Random curiosity

Discover secrets of ancient Rome!

If you want to be up to date with newest articles on website and discoveries from the world of ancient Rome, subscribe to the newsletter, which is sent each Saturday.

Subscribe to newsletter!

Subscribe to newsletter

Spelling error report

The following text will be sent to our editors: