In the United States Navy, Admiral of the Navy is traditionally considered the equivalent of a six-star Admiral. The rank has only been held by one person in history: George Dewey

Sleeve Insignia for Admiral of the Navy, worn by Admiral George Dewey

The rank Admiral of the Navy gained its equivalence as a six star rank during the Second World War, with the establishment of the rank of five-star Fleet Admiral.

During the preparations for the invasion of Japan, a proposal was raised by the Navy Department to appoint Chester Nimitz to the rank of Admiral of the Navy and grant him an insignia as a six-star admiral. Proposals for the new six star rank included changing the title to Flag Admiral. The proposal, however, was dropped and the United States Navy has never officially appointed anyone to the rank of six star admiral.

In the United States Army, the equivalent of Admiral of the Navy is known as General of the Armies.

see also List of US military leaders by rank