Admiral is a four-star commissioned officer rank in the United States Navy, the United States Coast Guard, and the United States Public Health Service Commissioned Corps with the pay grade of O-10. Admiral ranks above vice admiral and below fleet admiral in the Navy; the Coast Guard and the Public Health Service do not have an established grade above admiral. Admiral is equivalent to the rank of general in the other uniformed services. The National Oceanic and Atmospheric Administration Commissioned Officer Corps has never had an officer hold the grade of admiral. However, 37 U.S.C. § 201 of the U.S. Code established the grade for the NOAA Corps, in case a position is created that merits the four-star grade.

The United States Public Health Service Commissioned Corps is the uniformed service branch of the United States Public Health Service and one of the eight uniformed services of the United States. The commissioned corps' primary mission is the protection, promotion, and advancement of health and safety of the general public.