Kenneth "Ken" Montgomery was a Starfleet Admiral who served in the latter half of the 24th century. He was one of the key strategists in the Dominion War and believed by many to be one of the reasons the Federation won. (VOY novel: Homecoming)
In 2378, Montgomery began over-sight of Project Full Circle, charged with the examination as well as the removal of all Borg and future technology that was used to modify the USS Voyager during its seven year long journey to return to the Alpha Quadrant.
By 2381, Montgomery was the Admiral in command of the USS Voyager's battle fleet. During the Borg Invasion of 2381, Voyager commanding officer, Captain Chakotay, had to persuade Montgomery to petition Admiral Alynna Nechayev to reassign the ship to combat duty, including on the front line at the Azure Nebula. (ST - Destiny novel: Mere Mortals)
Following the invasion, Montgomery was among the flag officers who attended a briefing by Captain Jean-Luc Picard regarding the absorption of the Borg Collective into the Caeliar gestalt. (TNG novel: Losing the Peace)
Three months later, as Starfleet prepared to send an exploratory task-force, led by Voyager, to the Delta Quadrant, Montgomery ordered Captain Chakotay to undergo a psychological evaluation to assess his mental-readiness to return to duty. Along with Fleet Commander Willem Batiste, he eventually overruled the assessment of the evaluating officer, Counselor Hugh Cambridge, and relieved Chakotay of his command - assigning Captain Afsarah Eden in his place. (VOY novel: Full Circle)
After the death of Fleet Commander Eden and the resurrection of Vice Admiral Kathryn Janeway in September 2381, Montgomery appointed her Commander of the Full Circle Fleet. (VOY novel: The Eternal Tide)
However, before Admiral Janeway accepted the post, the offer was temporarily rescinded by Montgomery's immediate superior, Fleet Admiral Leonard James Akaar, the Commander-in-Chief of the Federation Starfleet, pending a psychological evaluation on Earth. Once she passed the evaluation, Montgomery and Akaar both signed off on the posting. (VOY novel: Protectors)
Admiral Montgomery resigned from Starfleet in 2382 when it was revealed that he intentionally looked the other way when officers within his chain of command came to him with concerns about illegal activity committed by Starfleet officers outside of his purview. (VOY novel: Atonement)