Praefectus

Praefectus, often with a further qualification, was the formal title of many military and civil officials in ancient Rome. Unlike elected magistrates, whose authority resided in their office, a praefectus exercised delegated authority from a higher-ranking official or the emperor. The title was used in both civic and military contexts.

In the military, prefects commanded units such as auxiliary cohorts, cavalry alae, or engineering corps, and in some cases served as acting legionary commanders. In civic administration, prefects could oversee specialized functions (such as grain supply or policing), govern provinces of strategic importance, or administer towns known as praefecturae that lacked self-governance.