Fleet admiral
Fleet admiral was a military rank, the equivalent of which was used by the service organizations of many civilizations. As a traditional grade, fleet admiral was the most senior flag officer rank of a naval organization, above all the flag admiral grades save for commander-in-chief.

In Starfleet, fleet admiral existed as a separate rank, but was also used as a title awarded and referring to officers wearing insignia of vice admiral or admiral, such as Fleet Admiral Shanthi. ()

While decorating to entertain Khan Noonien Singh aboard the  in 2267, Leonard McCoy commented that the ship must be expecting a fleet admiral for dinner. ()

Fleet admirals 
Klingon Defense Forces
 , a Klingon admiral

Starfleet
The following admirals wore the insignia for the fleet admiral rank:
, Commander in Chief
Bob, Chief of Staff
 Cartwright
 Kirsten Clancy, Commander in Chief
  (alternate reality)
 Morrow, Commander, Starfleet
 Charles Vance, Commander in Chief

The following admirals were referred to as fleet admirals but wore the rank insignia for vice admiral:
 Brackett
 Alynna Nechayev
 Shanthi

Appendices

Background information 
First mentioned in , the first fleet admiral seen on screen was Fleet Admiral Morrow in .

Robert Blackman's production notes during  described this rank as "5 Starfleet Admiral, gold framed bar w/5 dots." 

The  labeled this rank as "fleet admiral" referring to the , and "fleet admiral, five star" referring to its use on , , and .

, mistakenly identified the late 2270's-2350's admiral insignia as the fleet admiral insignia.

A deleted scene from  would have established a Fleet Admiral Gustafson who was at the time assigned to Starbase 218.

External links 
  
 

bg:Адмирал на флота
de:Flottenadmiral
es:Almirante General
fr:Amiral de la flotte
ja:元帥
nl:Vloot-admiraal
Military ranks
Titles