Commander-in-Chief of the Federation Starfleet

The Commander-in-Chief of the Federation Starfleet (also known as the C-in-C) was the senior most officer of the Federation Starfleet. The C-in-C served as a military advisor to the Federation President and Council, and had operational authority over the whole of the Federation Starfleet. Appointment to the position required the consent of the Federation Council. (TOS novel: The Ashes of Eden)

Starfleet's commander in chief was a position held by the senior fleet admiral, who took orders only from the Federation Council and its president. (Star Trek VI: The Undiscovered Country)

In the first half of the 23rd century, this position was held by Gene Roddenberry. (DIS: "The Vulcan Hello")

In 2399, this position was held by Admiral Kirsten Clancy. (PIC: "Maps and Legends")

Mirror universe

In the 23rd century, in the mirror universe, the commander in chief of the Imperial Starfleet was Gene Roddenberry. His name appeared on the dedication plaque of the ISS Discovery. (DIS: "Despite Yourself")

Years later, Spock rose to the position of commander in chief sometime between the 2260s and the 2360s. (DS9: "Crossover")

Commanders-in-Chief of the Federation Starfleet

• Admiral Bull Buchinsky (at least 2269 until 2270) (Grade unknown)
• Admiral Voysey (mid 2260s) (Grade unknown)
• Admiral Comsol (possibly Robert L. Comsol, from 2270)
• Grand Admiral Stephen Turner (at least 2285-)
• Grand Admiral John "Blackjack" Harriman (at least 2289-at least 2290)
• Grand Admiral William Smillie (at least 2293-2293)
• Grand Admiral Androvar Drake (2293-2293)
• Grand Admiral Margaret Sinclair-Alexander (at least 2311)
• Admiral Pavel Chekov (after 2311-before September 2371) (Grade unknown)
• Fleet Admiral Taela Shanthi (at least 2368-)
• Admiral Thomas Rickman (2377-January 2381)
• Admiral Edward Jellico (January 2381-February 2381 (Grade unknown)
• Admiral Victor Bordson (2381)
• Admiral Leonard James Akaar (2382)
• Fleet Admiral Kirsten Clancy (2399)
• Fleet Admiral Jorel Quinn (before 2409 -)
• Admiral Charles Vance (before 3189-)

Turner is not identified as C-in-C, but as a Grand Admiral; because the only on-screen C-in-C (Smillie) wears an insignia that identifies his grade as above Fleet Admiral, and wears a uniform bearing an extra gold stripe not seen on the uniforms of Fleet Admirals, it is assumed that Smillie's grade is Grand Admiral, and Turner's position is C-in-C. It is presumed that subsequent C-in-Cs of the same period, whose grades are not established in any source, also hold the rank of Grand Admiral.

This title is sometimes confused with Commanding Officer, Starfleet Command (Commander, Starfleet) and Chief of Staff for the Federation Starfleet (Starfleet Chief of Staff), both of which are separate titles.