Michael or Mike O'Brien may refer to:
Politicians Michael O'Brien (Fianna Fáil politician) (1933–2025), Irish councillor and mayor of Clonmel Michael O'Brien (Ohio politician) (born 1955), American politician in the state of Ohio Michael O'Brien (South Australian politician) (born 1949), Australian Labor Party member of the South Australian House of Assembly, 2002–present Micheal O'Brien (Canadian politician), Progressive Conservative Party of Canada candidate for the Canadian House of Commons Michael O'Brien (Victorian politician) (born 1971), Liberal Party of Australia member of the Victorian Legislative Assembly, 2006–present Michael H. O'Brien (1954–2018), American politician in the commonwealth of Pennsylvania Michael J. O'Brien (born 1939), American politician in the state of Iowa Michael John O'Brien (1851–1940), Canadian politician, railway builder, industrialist and philanthropist Mike O'Brien (British politician) (born 1954), United Kingdom Labour Party politician Mike O'Brien (Canadian politician), mayor of Fredericton, New Brunswick Mike O'Brien (Seattle politician) (born 1968), American politician Michael O'Brien (New Hampshire politician)
Sports Michael O'Brien (Australian rules footballer) (born 1980), West Coast Eagles Michael O'Brien (fencer) (born 1969), Irish fencer Michael O'Brien (hurling manager) (1933–2014), Irish Catholic priest and hurling manager Michael O'Brien (Irish sportsman), Irish association footballer, Gaelic footballer and cricketer in the 1920s Mike O'Brien (swimmer) (born 1965), American swimmer Micheál O'Brien (1923–2015), Irish Gaelic footballer and hurler Mike O'Brien (American football) (born 1956), American football player Mike O'Brien (hurler) (born 1978), Irish hurler Mikey O'Brien (born 1999), Irish hurler
Others Michael O'Brien (bishop) (1876–1952), Irish Roman Catholic bishop Michael O'Brien (American poet) (1939–2016), American poet Michael O'Brien (Canadian author) (born 1948), Canadian author Michael O'Brien (game designer), Australian game designer Michael O'Brien (historian) (1948–2015), American historian Michael O'Brien (unionist) (born 1949 or 1950), American labor union leader Michael O'Brien (musician) (born 1964), American musician Michael O'Brien (photographer) (born 1950), American photographer Michael K. O'Brien, visual effects artist Mike O'Brien (actor) (born 1976), American writer and performer on Saturday Night Live Mike O'Brien (game developer), co-founder, ArenaNet; game designer and programmer
Characters Guardsman (Michael O'Brien), a fictional character in the Iron Man comics Michael O'Brien, a fictional engineer character in the 1940 Christmas film Beyond Tomorrow
See also Mick O'Brien (disambiguation)