Lieutenant Barnaby was a Starfleet security officer serving on the USS Enterprise-D in 2370.

Barnaby transported down to the rogue Borg planet to search for Lieutenant Commander Data, and was one of the last to return to the ship. He relieved Ensign Taitt at tactical and served in that position under the temporary command of Dr. Beverly Crusher. He was skeptical of Taitt's abilities, but she soon proved herself after devising a plan to destroy the Rogue Borg ship using a solar fusion eruption. (TNG: "Descent, Part II")