Thomas O'Malley may refer to:
- Thomas Francis O'Malley (1889-1954), American politician
- Thomas O'Malley (congressman) (1903–1979), U.S. Representative from Wisconsin
- Thomas J. O'Malley (1868–1936), American politician, lieutenant governor of Wisconsin
- Thomas O'Malley (writer), Irish writer
- Thomas P. O'Malley (1930–2009), American Jesuit and academic
- Tom O'Malley (born 1960), former American Major League Baseball player
- Tom O'Malley (American football) (1925–2011), American football player
- T. J. O'Malley (1915–2009), American aerospace engineer
- Thomas O'Malley, the alley cat in the film The Aristocats