Namesakes
Terence Albert O'Brien
(m) 1600-1651 
Saints
Pat O'Brien
(m) 1899-1983
Notable Actors and Entertainers (actor)
Merle Oberon
(a.k.a. O'Brien) (f) 1911-1979
Notable Actors and Entertainers (actor)
Edward O'Brien
(m) 1914-1976
Olympic Medalists 1936 4x400 m relay (silver)
Edmond O'Brien
(m) 1915-1985
Notable Actors and Entertainers (actor)
Oscar Award Winners 1955 The Barefoot Contessa (actor)
Parry O'Brien
(m) 1932-2007
Olympic Medalists 1952; 1956; 1960 shot put (gold/silver)
Dusty Springfield
(a.k.a. O'Brien) (f) 1939-1999
Notable Musicians
Rock and Roll Hall-of-Famers 1999
Anne Rice
(a.k.a. O'Brien) (f) 1941-2021
Notable Writers
Ian O'Brien
(m) 1947-
Olympic Medalists 1964 swimming - 200 m breaststroke; swimming - 4x100 m medley relay (gold/bronze)
Conan O'Brien
(m) 1963-
Notable Actors and Entertainers (presenter)
Michael O'Brien
(m) 1965-
Olympic Medalists 1984 swimming - 1500 m freestyle (gold)
Dan O'Brien
(m) 1966-
Olympic Medalists 1996 decathlon (gold)
Ed O'Brien
(m) 1968-
Rock and Roll Hall-of-Famers 2019 Radiohead
Darrin "Snow" O'Brien
(m) 1969-
Notable Musicians
Kieran O'Brien
(m) 1973-
Notable Actors and Entertainers (actor)
Austin O'Brien
(m) 1981-
Notable Actors and Entertainers (actor)
Niall O'Brien
(m) 1981-
Notable Athletes (cricket)
Seán O'Brien
(m) 1987-
Notable Athletes (rugby)
Dylan O'Brien
(m) 1991-
Notable Actors and Entertainers (actor)
True O'Brien
(f) 1994-
Notable Actors and Entertainers (actor)