Admiral Fitzgerald is the Starfleet officer in The Mark of Gideon who denies Spock permission to beam down to Gideon in search of the missing Captain Kirk.
Admiral Fitzgerald is a senior Starfleet officer who appears on the Enterprise viewscreen in the Original Series episode The Mark of Gideon. When Kirk vanishes during transport and the Gideon council blocks every attempt to look for him, Spock appeals to Starfleet Command.
Fitzgerald tells him the matter belongs to the diplomats. Gideon is a prized candidate for Federation membership, its government forbids any visitors or sensor scans, and Starfleet will not risk an incident. Spock is ordered not to send anyone down.
Spock, with heavy irony about the uses of diplomacy, concludes that he must disobey. He beams to the coordinates given for Kirk and finds the captain on a perfect copy of the Enterprise built on the planet's surface.