The Julian Emperors
Following the death of Augustus Caesar, Rome was ruled by a succession of four emperors referred to by historians as the Julian Emperors. They are given this name due to the fact that each of these four emperors was related in some way to Julius Caesar.
The first of these emperors was Tiberius. Tiberius succeeded Augustus to the throne, and was his adopted son. He was a cruel and jealous leader, who accused many innocent people of treason against him.

Tiberius was succeeded by is grand nephew Caligula. Caligula was mentally ill, and displayed poor leadership as a result. He was eventually murdered by one of his own guards.
Caligula was followed to the thrown by Claudius, who was in ineffective leader, and who cared more about living a comfortable life, than ruling an empire. Claudius was followed to the thrown by Nero. Nero was a violent and cruel leader, who nearly bankrupt Rome through horse racing and music.