Julio-Claudian dynasty reign as being strongly influenced by his mother Agrippina, his tutor Seneca, and the Praetorian Prefect Burrus, especially in the first year. He was made Emperor over his step-brother, Claudius' son Britannicus, who he had killed. Agrippina was believed to have poisoned Claudius, having allegedly poisoned her second husband Gaius Sallustius Crispus Passienus. She had also arranged the deaths of Caligula's third wife, Lollia Paulina and Messalina's mother Domitia Lepida the Younger. She saw that the dynasty's numbers dwindle with the execution of Marcus Junius Silanus Torquatus, a grandson of Julia the Younger, to strengthen Nero's claim, having previously arranged
Roman emperor then create a rival lineage of Roman emperors in western Europe, the Holy Roman Emperors, which ruled the Holy Roman Empire for most of the period between 800 and 1806. These Emperors were never recognized as Roman emperors by the court in Constantinople. Modern historians conventionally regard Augustus as the first Emperor whereas Julius Caesar is considered the last dictator of the Roman Republic, a view having its origins in the Roman writers Plutarch, Tacitus and Cassius Dio. However, the majority of Roman writers, including Josephus, Pliny the Younger, Suetonius and Appian, as well as most of the ordinary people