Lieutenant Reginald "Reg" Endicott Barclay III was a highly-talented Human Starfleet systems diagnostic engineer who lived in the 24th century. He frequently displayed nervous behavior, demonstrated a noticeable lack in confidence, stammered profusely, was extremely introverted, and occasionally bumbled. These traits engendered the derision of some of his shipmates on the USS Enterprise-D – with some even going as far as calling him "Broccoli" behind his back or, on unfortunate occasions, to his face.
Although he may appear to be nervous and lacking in confidence, Reg Barclay is a highly talented Starfleet systems diagnostic engineer. Stationed aboard the U.S.S. Enterprise NCC-1701-D from 2366, Barclay had a tendency to spend more time inside the holodeck than in real social situations. Barclay also suffered from severe transporter phobia in 2369, although he seems to have overcome this psychological barrier.