Roman emperors were the rulers of the Roman Empire, which lasted from 27 BC to AD 476 in the West. The first emperor was Augustus, who established the imperial system after the fall of the Roman Republic. Emperors held significant power, overseeing military, political, and religious matters. Throughout history, there were many notable emperors, such as Nero, known for his controversial reign, and Trajan, celebrated for expanding the empire to its greatest territorial extent. The role of the emperor evolved over time, influencing the governance and culture of Rome and its provinces.