The rank of admiral of the fleet or fleet admiral was the highest naval rank of the Soviet Union from 1940 to 1955 and second-highest from 1962 to 1991.

Ivan Stepanovich Isakov, born Hovhannes Ter-Isahakyan, was a Soviet Armenian military commander, Chief of Staff of the Soviet Navy, Deputy USSR Navy Minister, and held the rank of Admiral of the Fleet of the Soviet Union. He played a crucial role in shaping the Soviet Navy, particularly the Baltic and Black Sea flotillas during the Second World War. Aside from his military career, Isakov became a member and writer of the oceanographic committee of the Soviet Union Academy of Sciences in 1958 and, in 1967, became an honorary member of the Armenian Soviet Socialist Republic's Academy of Sciences.