Chief of Staff for the Federation Starfleet

The Chiefs of Staff for the Federation Starfleet (also known as the Starfleet Chief of Staff) was a senior Federation Starfleet flag officer who ranked below the Commanding Officer, Starfleet Command. In some matters, the Starfleet Chief of Staff possessed autonomy from their immediate superior; the office's authority over Free Agents was among those matters. 

In the 2160s, there were five Joint Chiefs of Staff, representing the original five space fleets that made up the Federation Starfleet. The United Earth Space Probe Agency was responsible for exploration, the Andorian Imperial Guard specialized in the defense of the Federation's borders, the Tellar Space Administration handled operational support and supply, the Vulcan Space Council dealt with research and development and administration, and the Alpha Centauri Space Research Council provided research, funding, resources, logistical and administrative support. 

Starfleet Joint Chiefs of Staff
In the year 2163, these officers served as the Starfleet Joint Chiefs of Staff: In 2165, Admiral Gardner retired from Starfleet, and was succeeded by Admiral Jonathan Archer. 
 * Admiral Samuel Gardner - Chief of Staff of the UESPA (Retired, 2165)
 * Admiral Thy'lek Shran - Chief of Staff of the Andorian Imperial Guard
 * Admiral Mov chim Flar - Chief of Staff of the Tellar Space Administration
 * Fleet Commander T'Viri - Chief of Staff of the Vulcan Space Council
 * Admiral Alexis Osman - Chief of Staff of the Alpha Centauri Space Research Council


 * Chiefs of Staff for the Federation Starfleet:
 * Admiral Jonathan Archer (2165 - 1 January 2169 )
 * Fleet Admiral Arthur Mason (at least 2269 - )
 * Fleet Admiral Dai Mehkan (at least 2276 - )
 * Fleet Admiral Marcus van Diemen (at least 2240 - 2240 )
 * Fleet Admiral Harold Morrow (at least 2285 - 2285 )
 * Fleet Admiral Robert Bennett (at least 2287 - )
 * Fleet Admiral Les Landau (at least 2345 - )
 * Fleet Admiral (at least 2363 - at least 2375 )


 * This title is sometimes confused with Commander-in-Chief of the Federation Starfleet (The C-in-C) and Commanding Officer, Starfleet Command (Commander, Starfleet), both of which are separate titles.