In the fictional universe of Star Trek, fleet admiral is the highest commissioned rank of the Starfleet. The first mention of the rank fleet admiral, was by Dr. McCoy on ', in the episode Space Seed. It was not until ' that an actual fleet admiral was seen on camera, being the character of Fleet Admiral Morrow played by actor Robert Hooks. Three other fleet admirals would be seen in subsequent motion pictures.
''Star Wars''
In the Imperial Navy of Star Wars, fleet admiral is considered a senior Imperial military rank for those who command sector fleets or task forces. Due to the size of the Imperial Navy, however, the necessity exists for even higher ranks. As such, most fleet admirals answer to a high admiral who in turn answers to a moff, grand moff, or supreme moff. Imperial grand admirals and grand generals are specially appointed and outrank all personnel, military and civil, save Emperor Palpatine and his appointed executors. The insignia for an Imperial fleet admiral is six blue and red squares in a rectangle design. High admirals use the same rank badge, but only wear one code cylinder while fleet admirals wear two. An old style insignia for fleet admiral, used during the time of the first Death Star, comprised a single line of six red squares with three code cylinders. This was also the insignia for high general, the Imperial Army equivalent of fleet admiral. High General Tagge, of the first Death Star, wore the old style fleet admiral/high general insignia, while Fleet Admirals Piett and Ozzel, of Darth Vader's task force wore the later insignia version. However, both Admirals Ozzel and Piett can be seen wearing one code cylinder on their right shoulder and two on their left, rather than just having one cylinder on each side. It can be argued that the uniforms seen in The Empire Strikes Back portray the true code cylinder count for a fleet admiral based on film canon.
''One Piece''
In the fictional world of One Piece, the Fleet Admiral is the highest rank in the Marines, and the commander of the entire organization. As such, there is only one Fleet Admiral in the world at a time. His only superiors are the World Government Commander-in-Chief, the Gorosei and the World Nobles. Some of his capabilities includes to start a Buster Call and to summon the Admirals or any other Marine officer to a mission. Being the senior of the three Admirals, who are known as the World Government's "Greatest Military Powers", the Fleet Admiral is also presumed to be the most powerful Marine in the world in terms of fighting skills. The current Fleet Admiral is Sakazuki -formerly known as Admiral Akainu-, who won the position after defeating fellow Admiral Aokiji in a ten-day duel so ferocious that devastated the whole island of Punk Hazard and even changed its weather permanently.
''Ender's Game''
In the novel Ender's Game, a child soldier named Ender Wiggin is conscripted into a battle school for gifted youths. During what Ender believes to be a final exam scenario, he is actually placed in command of a starfleet that proceeds to destroy a menacing alien race, all the while with Ender believing that his command of this fleet is only a simulation. After learning the truth, Ender is told that he has been promoted to fleet admiral, and thus holds the rank at an age of no more than twelve years old.
