Fleet captain
Fleet captain was a title given to a senior captain with a different set of responsibilities than a starship captain. This may have been a higher rank than captain or even commodore, although it did not possess a permanent position in the rank hierarchy.

Imperial Klingon Fleet
In 2257, Kol-Sha mockingly asked L'Rell if she planned to make  a fleet captain too, after she announced that Tyler would be overseeing the construction of the new  battle cruiser. ()

Starfleet 
By the mid-23rd century, fleet captain was a senior line officer in the Federation Starfleet. 

In 2265, after promotion to fleet captain, Christopher Pike passed command of the starship  on to Captain James Kirk. In 2266, as a fleet captain, Pike was engaged in a training exercise aboard an antiquated class J starship. The vessel's baffle plate ruptured and many of the trainees were killed. A number were saved by Pike – at the cost of him being rendered a "complete invalid". Despite his catastrophic injuries, Pike remained on the active duty roster as a command-grade officer. This was primarily due to Starfleet Command not willing to retire Captain Pike from duty due to the sacrifice he had made while saving cadets. ()

In the 2260s, Fleet Captain Garth was one of Starfleet's most decorated captains, the hero of the Battle of Axanar. Garth was injured and recovered among the natives of Antos IV, where he learned of the Antosians' bizarre metamorphic biochemistry control. The strain on Garth's system was too much, he was driven insane by learning their abilities. His life was saved, but maddened, he ordered a starship to fire on the planet, the crew mutinied and Fleet Captain Garth was remanded to treatment at Elba II. ()

Apocrypha 
A fleet captain's grade was, according to apocryphal sources, indicated on uniforms worn in the 2260s by three full stripes ringing the sleeves of any such officer's tunic, as against the two and a half stripes of a captain who did not command an entire fleet, only a single ship.

Appendices

Background information 
The name plate on the door to Pike's room on Starbase 11 reads simply "Captain Christopher Pike," suggesting that the title "fleet captain" is an honorary title and not a rank.  Nevertheless, Kirk explicitly stated that Enterprise was summoned by "Fleet Captain Pike", whom he had met when Pike "was promoted to fleet captain." While not definitive, Pike was referred to as "fleet captain" only in the teaser of . The phrase "fleet captain" was never uttered in "Part II", nor was Pike addressed by that title in either part of the episode.

The  included a fleet captain insignia for use with the , though the insignia never appeared on screen and was not part of uniform designer Robert Fletcher's rank notes.

The Star Trek: The Next Generation Officer's Manual (p. 8) described fleet captain as a position held by the heads of ship design teams, with three fleet captains throughout all of Starfleet who were in charge of cruiser-, destroyer-, and escort-class ships respectively. The manual stated that the rank was comprised of five gold pips worn on a uniform collar and was senior to the rank of commodore.

Apocrypha
In the book "The Captain's Oath", Christopher Pike believed the title fleet captain to be a bureaucratic position as it meant being the chief of staff to a Starbase commander.  A fleet captain's duties included the deployment and operations of all starships underneath the starbase's authority and being able to lead the occasional diplomatic or scientific mission if the need arose.

External links 
 
 

bg:Капитан на флота
cs:Kapitán flotily
de:Fleet Captain
ja:先任大佐
nl:Vloot-kapitein
Military ranks