Peter O'Brien
Peter O'Brien may refer to:
Sportsmen
- Peter O'Brien (outfielder), MLB outfielder, 2015–present
- Pete O'Brien (1900s second baseman), MLB second baseman, 1901–1907
- Pete O'Brien (1890s second baseman), MLB second baseman, 1887–1890
- Pete O'Brien (first baseman), MLB first baseman, 1982–1993
- Peter O'Brien (Gaelic footballer), Gaelic football goalkeeper
- Peter O'Brien (rugby league), Australian rugby league footballer
- Peter O'Brien (hurler), Irish hurler
Others
- Peter O'Brien, 1st Baron O'Brien, also known as Sir Peter O'Brien, Irish lawyer and judge
- Peter O'Brien (actor), Australian actor
- Peter O'Brien (theologian), Australian New Testament scholar
- Peter O'Brien (Medal of Honor), American Civil War soldier and Medal of Honor recipient
- James O'Brien (New Zealand politician)