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- Mary McAleese (born 1951): President of Ireland 1997–2011
- her husband Martin McAleese: Ind Senator 2011–
- Timothy McAuliffe (1909–1985): Lab Senator 1961–1969, 1973–1983
- his daughter Helena McAuliffe-Ennis (born 1951): Lab (then PD) Senator 1983–1987
- Joseph MacBride (died 1938): SF TD Mayo West 1919–1921, Mayo North and West 1921–1923, CnaG TD Mayo South 1923–1927
- his nephew Seán MacBride (1904–1988): CnaP TD Dublin County 1947–1948, Dublin South–West 1948–1957
- Seán MacEntee (1889–1984): SF TD Monaghan 1919–1922, FF TD Dublin County/Townships/South East 1927–1969
- his son-in-law Conor Cruise O'Brien (1917–2008): Lab TD Dublin North–East 1969–1977, Senator 1977–1979, MEP 1973
- Conor's cousin Owen Sheehy-Skeffington (1901–1970): Ind Senator 1954–1957, 1965–1970
- Eoin MacNeill (1867–1945): SF/CnaG TD National University of Ireland 1919–1927
- his son-in-law Michael Tierney (1894–1975): CnaG TD Mayo North 1925–1927, NUI 1927–1932, Senator 1938–1944
- his grandson Michael McDowell (born 1951): PD TD Dublin South–East 1987–1989, 1992–1997, 2002–2007
- Tom McEllistrim (1894–1973): FF TD Kerry/Kerry North 1923–1969
- his son Tom McEllistrim (1926–2000): FF TD Kerry North 1969–1987, Senator 1987–1989, 1989–1992
- his grandson Tom McEllistrim (born 1968): FF TD Kerry North 2002–2011
- his son Tom McEllistrim (1926–2000): FF TD Kerry North 1969–1987, Senator 1987–1989, 1989–1992
- Joseph McLoughlin (1916–1991): FG TD Sligo–Leitrim 1969–1977
- his nephew Tony McLoughlin (born 1949): FG TD Sligo–North Leitrim 2011–
- Ray MacSharry (born 1938): FF TD Sligo–Leitrim 1969–1988, MEP Connacht–Ulster 1984–1989
- his son Marc MacSharry (born 1973): FF Senator 2002–
- MacSwiney see Brugha
- Tadhg Manley (1893–1976): FG TD Cork South 1954–1961
- his nephew Liam Burke (1928–2005): FG TD Cork City 1969–1977, 1979–1981, TD Cork North–Central 1981–1989, 1992–2002
- John Mannion, Snr (1907–1978): FG TD Galway West 1951–1954, Senator 1954–1957, 1961–1969
- his son John Mannion, Jnr (1944–2006): FG TD Galway West 1977–1981, Senator 1969–1977, 1981–1983
- Con Meaney (died 1970): FF TD Cork North 1937–1943, Cork Mid 1961–1965
- his son Thomas Meaney (born 1931): FF TD Cork Mid/Cork North–West 1961–1982
- Liam Mellows (1895–1922): SF TD Galway East, Meath North 1918–1922, Galway 1921–1922
- his brother Barney Mellows (c. 1896–1942): SF TD Galway 1923–1927
- Matthew Minch (1857–1921): INF/IPP MP South Kildare 1892–1903
- his son Sydney Minch (1893–1970): CnaG TD Kildare 1932–1937, Carlow–Kildare 1937–1938
- Jim Mitchell (1946–2002): FG TD Dublin Ballyfermot/Dublin West/Dublin Central 1977–2002
- his brother Gay Mitchell (born 1951): FG TD Dublin South–Central 1981–2007, MEP Dublin 2004–
- Joe Mooney (died 1988): FF Senator 1961–1965
- his son Paschal Mooney (born 1947): FF Senator 1987–2007, 2010–
- Michael Moynihan (1917–2001): Lab TD Kerry South 1981–1992
- his daughter Breeda Moynihan-Cronin (born 1953): Lab TD Kerry South 1992–2007
- Eugene Mullen (c. 1898–?): FF TD Mayo South June–Sept 1927
- his brother Thomas Mullen (c. 1897–1966): FF TD Dublin County 1938–1943
- Rónán Mullen (born 1970): Ind Senator 2007–
- his first cousin Michael Mullins, FG Senator 2011–
- Michael Pat Murphy (1919–2000): Lab TD Cork South–West 1951–1981
- his son-in-law John O'Donoghue (born 1956): FF TD Kerry South 1987–2011
Read more about this topic: Families In The Oireachtas