Brad Yacobian was a Starfleet officer in the 24th century.
In 2371, he was a crewmember aboard the USS Voyager. He was among the crew stranded in the Delta Quadrant, when Voyager was forcefully brought there by the Caretaker.
In 2372, as a lieutenant commander, he was listed on the Planetary Geosciences Division duty roster. (VOY: "Parturition")
In 2374, he was listed on a crew manifest. (VOY: "The Killing Game", crew manifest)