The Senate of the Roman Empire was a political institution in the ancient Roman Empire. After the fall of the Roman Republic, the constitutional balance of power shifted from the Roman Senate to the Roman Emperor. Beginning with the first emperor, Augustus, the Emperor and the Senate were technically two co-equal branches of government. In practice, however, the actual authority of the imperial Senate was negligible, as the Emperor held the true power of the state. As such, membership in the senate became sought after by individuals seeking prestige and social standing, rather than actual authority. During the reigns of the first Emperors, legislative, judicial, and electoral powers were all transferred from the "Roman assemblies" to the Senate. However, since the control that the Emperor held over the senate was absolute, the Senate acted as a vehicle through which the Emperor exercised his autocratic powers.

The Roman Senate was the highest and constituting assembly of ancient Rome and its aristocracy. With different powers throughout its existence it lasted from the first days of the city of Rome as the Senate of the Roman Kingdom, to the Senate of the Roman Republic and Senate of the Roman Empire and eventually the Byzantine Senate of the Eastern Roman Empire, existing well into the post-classical era and Middle Ages.