Sextus Tigidius Perennis (died 185) was a prefect of the Roman imperial bodyguard, known as the Praetorian Guard, during the reigns of the emperors Marcus Aurelius and Commodus. Under the latter, Perennis was the man who exercised the chief responsibilities of government in the Roman Empire. In 185 however, Perennis was implicated in a plot to overthrow the emperor by his political rival Marcus Aurelius Cleander, and executed under orders of Commodus.