Niall O'Brien may refer to:

Niall O'Brien (actor) (1946–2009), Irish actor Niall O'Brien (cricketer) (born 1981), Irish cricketer Niall O'Brien (hurler) (born 1994), Irish hurler Niall O'Brien (priest) (1939–2004), Irish Columban missionary priest

See also Neil O'Brien (disambiguation)