Brian O'Brien may refer to: Brian O'Brien (optical physicist) (1898–1992), American optical physicist and the founder of the Air Force Studies Board Brian O'Brien (space scientist) (1934–2020), Australian physicist and space scientist Brian O'Brien (rugby union) (1939–2023), Irish rugby union player and coach Brian O'Brien (journalist) (1922–1982), New Zealand sports journalist and politician Clock (character), a fictional crime-fighter whose alter ego is Brian O'Brien
See also Brian O'Brian, an Italian-American series of television shorts