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
See also
Peter O'Brian (disambiguation)