John O'Brien

John O'Brien may refer to:

American

 * John O'Brien (Ohio politician) (1932–1985), former member of the Ohio House of Representatives
 * John D. O'Brien, state senator in the 1997–1998 Massachusetts legislature
 * John F. O'Brien (secretary of state) (c. 1850–1927), Secretary of State of New York, 1903–1906
 * John F. O'Brien (judge) (1874–1939), New York Court of Appeals judge
 * John H. O'Brien, 4th Fire Commissioner of the City of New York
 * John J. O'Brien (civil servant) (1919–2001), investigated the assassination of President John F. Kennedy
 * John J. O'Brien (commissioner), former commissioner of the Massachusetts Probation Service
 * John P. O'Brien (1873–1951), 98th mayor of New York City
 * John L. O'Brien (1911–2007), American politician in the Washington House of Representatives

Irish

 * John O'Brien (bishop) (died 1767), Irish Bishop of Cork and Cloyne
 * John O'Brien (Irish politician) (1794–1855), MP for Limerick City in the UK Parliament 1841–1852
 * John O'Brien (priest) (1931–2008), Irish Roman Catholic priest and musician
 * John Thomond O'Brien (1786–1861), Irish soldier in the Argentine War of Independence
 * Joseph O'Sullivan, who assumed the name "John O'Brien" while under arrest for the 1922 assassination of Sir Henry Wilson

British

 * John O'Brien (British politician) (died 1982), far right figure, onetime leader of the British National Front
 * Sir Terence O'Brien (colonial administrator) (John Terence Nicholls O'Brien, 1830–1904), British surveyor, engineer and colonial governor

Canadian

 * John O'Brien (admiral) (1918–1996), commander of the Royal Canadian Navy
 * John O'Brien (Canadian politician) (1847–1917), merchant and member of the Legislative Assembly of New Brunswick

New Zealand

 * John O'Brien (New Zealand politician) (1925–1990), New Zealand political candidate and party leader

Australian

 * John O'Brien (Australian politician) (1866–1932), Member of the Queensland Legislative Assembly
 * John O'Brien (Australian Army officer) (1908–1980), Australian major general and Mayor of Woollahra

Baseball

 * John O'Brien (outfielder) (1851–1914), baseball outfielder
 * John O'Brien (second baseman) (1866–1913), baseball infielder
 * Johnny O'Brien (born 1930), 1950's baseball second baseman
 * Cinders O'Brien (John F. O'Brien, 1867–1892), baseball pitcher

Footballers

 * John O'Brien (Dublin footballer), senior inter-county Gaelic footballer for Dublin and Round Towers, Clondalkin
 * John O'Brien (Louth footballer) (born 1985), Gaelic footballer for Louth
 * John O'Brien (soccer) (born 1977), American soccer player
 * Jon O'Brien (born 1961), English footballer

Other sports

 * John O'Brien (basketball, born 1888) (1888–1967), American basketball referee and executive
 * John O'Brien (basketball, born 1916) (1916–1994), American professional basketball player in the 1940s
 * John O'Brien (boxer) (1937–1979), Scottish boxer of the 1960s and '70s
 * John O'Brien (cricketer, born 1961), English cricketer
 * John O'Brien (Irish cricketer) (1866–1920), Irish cricketer
 * John O'Brien (hurler) (born 1982), Irish hurler
 * John O'Brien (rower) (1927–1995), New Zealand representative rower
 * John O'Brien (tennis) (born 1932), Australian tennis player and hostage in the 2014 Sydney hostage crisis
 * John O'Brien (water polo) (1931–2020), Australian Olympic water polo player
 * John Ambrose O'Brien (1885–1968), founding owner of the Montreal Canadiens ice hockey team
 * John O'Brien (businessman), British businessman

Other people

 * John O'Brien (marine artist) (1831–1891), Canadian marine artist
 * John O'Brien, the original name of stage actor John T. Raymond (1836–1887)
 * John O'Brien (poet) (1878–1952), Australian priest, poet and author
 * John B. O'Brien (1884–1936), American actor and director
 * John O'Brien (publisher), Irish American publisher and academic
 * John O'Brien (novelist) (1960–1994), American author
 * John O'Brien (filmmaker) (born 1962), Vermont film director
 * John O'Brien (advocate), disability inclusion advocate and writer
 * John O'Brien (screenwriter), screenwriter of Fireflies and K-9
 * John Roger O'Brien (1903–1982), birth name of Jack O'Brien (jazz pianist)