Patrick Brennan may refer to:

• P. J. Brennan (born 1986), American actor
• Pádraig Brennan (born 1978), Irish Gaelic football player
• Patrick Brennan (police officer), Irish politician, TD 1921–1923, Assistant Commissioner of the Garda Síochána
• Paudge Brennan (Patrick Brennan, 1922–1998), Irish Fianna Fáil TD and Senator
• Patrick Brennan (lacrosse) (1877–1961), who represented Canada at the 1908 Summer Olympics
• Paddy Brennan (born c. 1930), Irish comics artist
• Paddy Brennan (jockey) (born 1981), Irish jockey
• Patrick Brennan (politician) (born 1953), Republican politician in the Vermont House of Representatives
• Patrick Brennan (actor) (born 1974), American actor
• Patrick Thomas Brennan (1901–1950), American Catholic missionary priest