Michael Fuller was a male Human Starfleet security officer who served in the 23rd century. In 2267, he came out of retirement to serve on the USS Enterprise (NCC-1701). (TOS - Errand of Fury novels: Seeds of Rage, Demands of Honor, Sacrifices of War)
Born in 2215, Michael Fuller became a Starfleet security officer in 2242 and was assigned to the USS Endeavour under Captain Shannon, where he was the ship's ranking officer to survive of the Battle of Donatu V. Alongside Admiral William Jefferies of the USS Constitution (NX-1700) and Lieutenant (acting Captain) Robert Justman of the USS Yorkshire, Ensign Fuller negotiated the ceasefire after the battle ended in a draw. For his actions during the battle, Ens. Fuller received the Starfleet Medal of Honor.
Just before he deployed on the Endeavor, Michael learned that his girlfriend with whom he had recently broken up with was pregnant. When he returned home, Alison had moved on with a new boyfriend, and so Michael took an assignment on the USS Republic, despite being offered a position on one of the newly-constructed (but not yet finished) Constitution-class starships.
By 2250, Michael held the rank of Lieutenant and was a Section Chief for the Republic's security forces. It was then that he met a young officer named James T. Kirk, along with another officer named Benjamin Finney.
Michael eventually retired from Starfleet as a Security Section Chief in the early 2260s, having turned down multiple offers of promotion throughout his 20-year career. However, after the death of his son on Starbase 42, Michael contacted Admiral Herbert Solow and requested a return to active duty.
After the signing of the Organian Peace Treaty, Lt. Fuller left the Enterprise, having accepted a long-standing offer to become an instructor at Starfleet Academy. (TOS - Errand of Fury novels: Seeds of Rage, Demands of Honor, Sacrifices of War)