Captain in the U.S. Army (USA), U.S. Marine Corps (USMC), U.S. Air Force (USAF), and U.S. Space Force (USSF) is a company-grade officer rank, with the pay grade of O-3. It ranks above first lieutenant and below major. It is equivalent to the rank of lieutenant in the Navy/Coast Guard officer rank system and is different from the higher Navy/Coast Guard rank of captain. The insignia for the rank consists of two silver bars, with slight stylized differences between the Army/Air Force version and the Marine Corps version.

A company is a military unit, typically consisting of 100–250 soldiers and usually commanded by a major or a captain. Most companies are formed of three to seven platoons, although the exact number may vary by country, unit type, and structure.