Admiral
From Halopedia, the Halo wiki
Admiral is a senior commissioned officer rank of the UNSC Navy.
During peacetime it is the highest military rank, and is equal with the rank of General in the UNSC Marine Corps. However, during times of war, senior Admirals may be promoted to the rank of Fleet Admiral, which outranks Admiral.
While Admiral is a rank of its own, the title "Admiral" is often used to refer to any of the flag officer ranks of the UNSC Navy:
