Barclay is an extremely talented Starfleet systems diagnostic engineer, but was timid and awkward in social situations. Having reclusive tendencies, Barclay created a rich fantasy life on the U.S.S. Enterprise-D's holodeck. He was able to overcome this by counseling sessions with Counselor Deanna Troi. Barclay is fond of investigating the Starfleet Medical Database, often convinced he has a rare and deadly disease. He had a strong phobia of being transported until 2369, when he was forced to participate in the U.S.S. Yosemite rescue mission.

Starfleet History
Attended Starfleet Academy
2362 Attended Daystrom Institute.
2362 Posted U.S.S. Zhukov NCC-62136, Diagnostic Engineer.
2366 Commendation for Excellent Service by Capt. Gleason, U.S.S. Zhukov.
2366 Posted to U.S.S. Enterprise NCC-1701-D, Diagnostic Engineer.
2367 A Cytherian probe temporarily increased neurochemical activity, causing him to take control of the Enterprise compute.r
2369 Barclay discovers quasi-energy microbes in the U.S.S. Yosemite NCC-19002 transporter beam.
2370 While being treated for Urodelean flu, a synthetic T-cell caused Barclay's introns to mutate and become airborne, infecting the Enterprise crew causing them to de-evolve. Dr. Beverly Crusher named this disease Barclay's Proto-morphosis Syndrome.
2371 U.S.S. Enterpise NCC-1701-D was destroyed at Veridian III.
2371 Assisted Dr. Lewis Zimmerman in programming the Emergency Medical Holographic (EMH) Program at Jupiter Station Holoprogramming Center.
2372 Posted to Sovereign-class U.S.S. Enterprise NCC-1701-E
2373 U.S.S. Enterprise NCC-1701-E succeeded in stopping the Borg's temporal incursion. Assisted in rebuilding Zefram Cochrane's warp ship, The Phoenix.

Reginald Barclay was first seen in "Hollow Pursuits" (TNG).