prefect

noun

• An official of Ancient Rome who controlled or superintended a particular command, charge, department, etc.

  "the prefect of the aqueducts; the prefect of a camp, of a fleet, of the city guard, or of provisions; the pretorian prefect, who was commander of the troops guarding the emperor's person"

• The head of a department in France.
• The head of a prefecture in Japan.
• A school pupil in a position of power over other pupils.
• A commander.