Nero became Roman emperor in 54 CE after the death of Claudius, who had adopted him as his successor. At sixteen he initially governed with powerful advisers, particularly the philosopher Seneca and the praetorian prefect Burrus, while his mother Agrippina sought influence over the new regime. Relations within the imperial family soon became violent. Claudius's son Britannicus died in 55, allegedly poisoned, and Nero arranged Agrippina's killing in 59. The details survive largely through later writers hostile to his rule, requiring caution about their dramatic reconstructions.

Nero's reign included serious military and provincial crises as well as court politics. Boudica's revolt in Britain in 60–61 exposed the violence and exploitation accompanying Roman conquest before the rebellion was suppressed. In the east, campaigns and negotiation over Armenia eventually produced an accommodation with Parthia. Nero celebrated the Armenian king Tiridates' visit to Rome in 66 as a diplomatic success.

The great fire of Rome in 64 destroyed large areas of the city. Nero organized relief and rebuilding, including new building requirements, but also appropriated extensive space for his Golden House palace. Accusations that he deliberately started the fire are not established by reliable evidence. Tacitus reports that Nero brutally persecuted Christians as scapegoats, describing executions of exceptional cruelty. The discovery of the Pisonian conspiracy in 65 brought widespread repression, including Seneca's forced suicide. Confiscations and punishment deepened tensions between the emperor and members of the elite.

Nero devoted conspicuous attention to singing, acting, and chariot racing, activities that offended Roman expectations of imperial dignity when performed publicly. His journey to Greece in 66–67 combined performances, competitions, and political spectacle. Such interests could also attract popular support and should not automatically be treated as proof that he abandoned government altogether. Revolts in Gaul and Spain in 68, followed by the loss of praetorian support and Senate condemnation, destroyed his position. He killed himself in June, ending the Julio-Claudian dynasty and opening a period of civil war. Later historical writing fixed the image of a monstrous ruler, but its accusations must be assessed individually rather than accepted or rejected as a whole.