An oil canvas portrait of Admiral Horatio Nelson, 1st Viscount Nelson from 1799

Admiral is one of the highest ranks in some navies, and in many navies is the highest rank. In the Commonwealth nations and the United States, a "full" admiral is equivalent to a "full" general in the army, and is above vice admiral and below admiral of the fleet, or fleet admiral. In NATO, admirals have a rank code of OF-9 as a four-star rank.