Captain is a commissioned officer rank of the UNSC Navy, and is the Naval equivalent of a Colonel in the UNSC Marine Corps, UNSC Air Force and UNSC Army. Navy Captains typically command a single ship - typically a class larger than a frigate but smaller than a carrier. Navy Captains may also command a battlegroup or a small fleet if they are the senior-most officer present. Captains are sometimes referred to informally as "Skipper" or "the Old Man."