Peter O'Brien

Peter O'Brien may refer to:

Sportsmen

 * Peter O'Brien (outfielder) (born 1990), MLB outfielder, 2015–present
 * Pete O'Brien (1900s second baseman) (1877–1917), MLB second baseman, 1901–1907
 * Pete O'Brien (1890s second baseman) (1867–1937), MLB second baseman, 1887–1890
 * Pete O'Brien (first baseman) (born 1958), MLB first baseman, 1982–1993
 * Peter O'Brien (Gaelic footballer), Gaelic football goalkeeper
 * Peter O'Brien (rugby league) (1928–2016), Australian rugby league footballer
 * Peter O'Brien (hurler) (born 1987), Irish hurler

Others

 * Peter O'Brien, 1st Baron O'Brien (1842–1914), known as Sir Peter O'Brien, Bt, Irish lawyer and judge
 * Peter O'Brien (actor) (born 1960), Australian actor
 * Peter O'Brien (theologian) (born 1935), Australian New Testament scholar
 * Peter O'Brien (Medal of Honor) (1842–1898), American Civil War soldier and Medal of Honor recipient