There have been many Roman emperors who have been known for their brutality, and it is difficult to determine which one is the most infamous. Some examples of Roman emperors who have been known for their brutality include Caligula, who was known for his erratic and tyrannical behavior, and Nero, who was known for his persecution of Christians and for his extravagance. Additionally, many Roman emperors were known for their use of violence and military force to achieve their goals, including Julius Caesar, who was known for his military campaigns and for his role in the fall of the Roman Republic. It is important to note that many historical figures, including Roman emperors, had both virtues and vices, and it is not fair to judge them solely on their negative qualities.