A commandant is the commanding officer in charge of a military base, academy, or institution. The Commandant of the Marine Corps, for example, is the highest-ranking officer in the entire U.S. Marine Corps, responsible for the training, organization, and leadership of all Marines. At the U.S. Naval Academy or Coast Guard Academy, the commandant oversees the day-to-day lives of students, ensuring they follow military discipline and develop into capable officers.

A commandant holds the authority to give orders and make important decisions for everyone under their leadership. Unlike a general who might lead troops in battle, a commandant typically focuses on running an installation, training facility, or organization.

Think of a commandant as similar to a principal at a school, but with military authority. Just as a principal runs a school and sets its tone, a commandant runs a military facility and ensures it operates according to military standards and traditions.