- Manolis AndronikosCitizenship: GreeceBorn: October 23, 1919
- Manuel de AbreuCitizenship: BrazilBorn: January 4, 1894
- Marc BirkigtCitizenship: SwitzerlandBorn: March 8, 1878
- Marc BuieCitizenship: United StatesBorn: 1958
- Marc DelafontaineCitizenship: SwitzerlandBorn: March 31, 1838
- Marcel BichCitizenship: FranceBorn: July 29, 1914
- Maria MontessoriCitizenship: Kingdom of ItalyBorn: August 31, 1870
- Marion RosenCitizenship: GermanyBorn: June 24, 1914
- Mark MothersbaughCitizenship: United StatesBorn: May 18, 1950
- Martin SchadtCitizenship: SwitzerlandBorn: August 16, 1938
- Mary Anne FallowsCitizenship: Kingdom of Great BritainBorn: March 14, 1796
- Mary Ethel MacLeodCitizenship: CanadaBorn: December 15, 1856
- María Ángeles Mezquíriz IrujoCitizenship: SpainBorn: February 1929
- Masanori HirasawaCitizenship: JapanBorn: 1956
- Masaru AraiCitizenship: JapanBorn: 1952
- Masaru MukaiCitizenship: JapanBorn: 1949
- Maurice AllaisCitizenship: FranceBorn: May 31, 1911
- Maximilian Bircher-BennerCitizenship: SwitzerlandBorn: August 22, 1867
- Meg SchwambCitizenship: United StatesBorn: 1984
- Michael J. ReddyCitizenship: United StatesBorn: March 4, 1944
- Michael van LangrenBorn: 1598Occupation: astronomer
- Michał KusiakCitizenship: PolandBorn: 1986
- Michel MayorCitizenship: SwitzerlandBorn: January 12, 1942
- Michel-Claude WeissCitizenship: FranceBorn: November 8, 1939
- Mikami SanjiCitizenship: JapanBorn: October 29, 1865
- Mikhail Evgenievich MassonCitizenship: Soviet UnionBorn: December 3, 1897
- Milan AntalCitizenship: SlovakiaBorn: September 19, 1935
- Miyoshi ManabuCitizenship: JapanBorn: January 4, 1862
- Moain SadeqCitizenship: CanadaBorn: 1955
- Moheschunder BannerjeeCitizenship: IndiaBorn: 1800
- Morito ŌmiyaCitizenship: JapanBorn: 1919
- Moshe ben MaimonBorn: April 6, 1135Occupation: astronomer
- Motohide TamuraCitizenship: JapanBorn: 1959