-Brutus: Despite his noble intentions to preserve Rome's republic and prevent Caesar from becoming a tyrant, Brutus' ambition to achieve that goal ultimately leads to his demise and the defeat of the conspirators.
-Cassius: Driven by his desire for power and reputation, Cassius manipulates Brutus and other conspirators to join him in assassinating Caesar. His ambition clouds his judgment and leads to disaster for the conspirators.
-Caesar: Julius Caesar's ambition for power and glory motivates his actions throughout the play. His desire to become the sole ruler of Rome leads him to make decisions that ultimately result in his assassination.
Overall, the characters' ambitions drive the plot of Julius Caesar, resulting in a dramatic exploration of the consequences and pitfalls of unbridled personal desire.