Admiral Harry Morrow
Fleet Admiral Harry Morrow served as Commander, Starfleet in 2285.
He conducted an inspection of the USS Enterprise that year after it suffered severe damage in a battle with the USS Reliant, which had been hijacked by the genetically-enhanced Khan Noonien Singh.
Despite being a close friend of Rear Admiral James T. Kirk, Morrow refused to allow Kirk and his crew to return to the Genesis Planet, stating that the planet had become a subject of galactic debate and controversy.
When confronted again by Kirk for permission to return to Genesis, Morrow threatened Kirk with the loss of his career. Kirk ignored Morrow's threats and stole the Enterprise from spacedock, forcing Morrow to issue orders to the newly-christened USS Excelsior to pursue the older ship.
During the investigation of the Genesis Planet, Captain J.T. Esteban reported directly to Morrow via coded, priority one communiques. (Star Trek III: The Search for Spock)
Kirk was later charged with disobeying direct orders from Morrow; this charge resulted in his demotion from admiral to captain. (Star Trek IV: The Voyage Home)
Background
Admiral Morrow was portrayed by Robert Hooks in Star Trek III. He was intended to reprise Star Trek IV, but was later replaced with Admiral Cartwright. It is unclear whether or not Morrow resigned his commission as a Starfleet admiral and was succeeded by Cartwright by the time of Star Trek IV: The Voyage Home.
Morrow is the only Starfleet admiral to be referred to by the prestigious title of "Commander of Starfleet", although it is unclear as to the specific function of the position. It is perhaps equivalent to the position held by Admiral Bill in Star Trek VI: The Undiscovered Country, or Admiral Leyton in DS9: "Paradise Lost", though this is conjecture and unsupported in canon.