Reginald Barclay
- Full Name: Reginald Endicott Barclay III
- Species: Human
- Gender: Male
- 2366: Lieutenant junior grade, diagnostic engineer, Starfleet; USS Zhukov (TNG: "Hollow Pursuits")
- 2366: Lieutenant junior grade, diagnostic engineer, Starfleet; USS Enterprise (TNG: "Hollow Pursuits", "The Nth Degree", "Realm of Fear", "Ship in a Bottle", "Genesis")
- Late 2370: Lieutenant junior grade, diagnostic engineer, Starfleet; Jupiter Station (VOY: "Projections")
- Assigned to original Emergency Medical Hologram project, interpersonal subroutine evaluation (VOY: "Projections")
- By 2372: Lieutenant, diagnostic engineer, Starfleet; USS Enterprise (Star Trek: First Contact)
- 2374: Lieutenant, diagnostic engineer, Starfleet; Pathfinder Project, Starfleet Communications (VOY: "Pathfinder", "Life Line", "Inside Man", "Author, Author", "Endgame")