Patrick O'Brien may refer to:
- Patrick Cotter O'Brien (1760âÂÂ1806), the tallest person alive in his lifetime
- Patrick O'Brien (Australian politician) (1810âÂÂ1882), politician in Victoria, Australia
- Sir Patrick O'Brien, 2nd Baronet (1823âÂÂ1895), Irish politician
- Patrick Joseph O'Brien (1835âÂÂ1911), Member of Parliament for North Tipperary, 1885âÂÂ1906
- Pat O'Brien (Irish politician) (Patrick O'Brien, c. 1847âÂÂ1917), Irish Nationalist MP in the United Kingdom Parliament
- Patrick O'Brien (footballer, born 1875) (1875âÂÂ1951), Scottish footballer
- Patrick O'Brien (footballer, born 1884) (1884âÂÂ?), Scottish footballer and surgeon
- Patrick O'Brian (1914âÂÂ2000), English novelist and translator
- Patrick K. O'Brien (born 1932), British academic and historian
- Patrick O'Brien (political scientist) (1937âÂÂ1998), politics professor, University of Western Australia
- Patrick O'Brien (musician) (1947âÂÂ2014), American musician and lutenist
- Patrick Thomas O'Brien (born 1951), American actor
- Patrick O'Brien (artist) (born 1960), illustrator and author of children's books
See also