The emperor credited with the institutionalization of the Roman Empire is Augustus, originally known as Octavian. He became the first emperor in 27 BCE, transforming Rome from a republic to an empire through a series of political reforms and consolidating power. Augustus initiated the Pax Romana, a lengthy period of relative peace and stability across the empire, which enhanced trade, infrastructure, and culture. His reign set the foundation for future emperors and marked a significant turning point in ancient Roman governance.