Commander Elias A. Vaughn was a Starfleet officer who in the 2370s was over one-hundred years old and an officer with eighty years experience in Starfleet Intelligence, Special Operations and Tactical.
Despite his relativity low rank (retained in order to maintain a low profile), Vaughn was on a first name basis with most of the Admiralty and had a higher security clearance than some.
Vaughn was a critical player in several crucial events in Starfleet history. Among them, the Tomed Incident, the Betreka Nebula Incident, the disaster at Arvada III, the civil war on Beta VI, and the liberation of Betazed from the Dominion.
Then, after a chance encounter with the Bajoran Orb of Memory, Vaughn decided to pursue his lost dream of being an explorer. After taking the vacant First Officers position at Federation starbase Deep Space 9 at age 101, Elias Vaughn commanded the USS Defiant on a three-month mission of exploration in the Gamma Quadrant and continued to contribute to Starfleet.