Mathieu may refer to:
In places:
- Mathieu, Calvados, a commune of the Calvados département in France
In mathematics:
- Claude-Louis Mathieu (1783–1875), French mathematician and astronomer
- Émile Léonard Mathieu (1835–1890), French mathematician
- Mathieu function, special function useful for treating a variety of interesting problems in applied mathematics
- Mathieu transformation, subgroup of canonical transformations in classical mechanics.
- Mathieu groups, a family of five sporadic simple groups
In sports:
- Mathieu Biron (born 1980), Canadian hockey defenceman
- Mathieu Bois (born 1988), Canadian breaststroke swimmer
- Mathieu Flamini (born 1984), French football player currently playing for A.C. Milan in Italy
- Jérémy Mathieu (born 1983), French football player currently playing for Valencia CF in Spain
- Maurice Mathieu, French badminton player
- Paul-Henri Mathieu (born 1982), French tennis player
- Simone Mathieu (1908–1980), French tennis player
- Tyrann Mathieu (born 1992), American football player formerly played for the LSU Tigers.
- Mathieu Montcourt (1985-2009), French tennis player
- Mathieu Schneider (born 1969), American hockey defenseman
- Mathieu Valbuena (born 1984), French football player currently playing for Marseille in France
In other fields:
- Mathieu Kérékou (born 1933), President of Benin from 1972 to 1991 and again from 1996 to 2006
- André Mathieu (1929–1968), Canadian pianist and composer
- David-Maurice-Joseph Mathieu de La Redorte (1768–1833), French general of the Napoleonic era
- Gail D. Mathieu, former United States ambassador to Namibia
- Georges Mathieu (1921–2012), French painter
- Marc-Antoine Mathieu, comic book author and winner of the Prix de la critique
- Michel Mathieu (Canadian politician) (1838-1916), Canadian politician
- Mireille Mathieu (born 1946), French singer
- W. A. Mathieu (born 1937), composer, musician, and educator
- Mathieu Orfila (1787–1853), Spanish-born French toxicologist and chemist