The praefectus vigilum (pl.: praefecti vigilum) was, starting with the reign of the Emperor Augustus, the commander of the city guards in Rome (cohortes vigilum or vigiles), whom were responsible for maintaining peace and order at night--a kind of fire and security police.

An imperial official in Ancient Rome who was charged with the supervision of the grain supply to the city of Rome.

The praefectus urbanus, also called praefectus urbi or urban prefect in English, was prefect of the city of Rome, and later also of Constantinople.