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- John Mabry (born 1970), professional baseball player; born in Wilmington
- Isaac J. MacCollum (1889–1968), physician and Lieutenant Governor of Delaware
- Thomas MacDonough (1783- 1825), United States Navy commodore, victor of the Battle of Lake Champlain in the War of 1812
- Jack A. Markell (born 1960), State Treasurer and Governor of Delaware
- Edward L. Martin (1837–1897), lawyer and U. S. Representative from Delaware
- Joshua H. Marvil (1825–1895), merchant and Governor of Delaware
- Joseph Maull (1781–1846), General Assembly and Governor of Delaware
- James D. McGinnis (1932–2009), realtor and Lieutenant Governor of Delaware.
- Eleazer McComb (died 1798), Continental soldier and Continental Congressman from Delaware
- Harris B. McDowell, Jr. (1906–1988), General Assembly and U. S. Representative from Delaware
- Bernie McInerney (born 1936), actor; born in Wilmington
- Thomas McKean (1734–1817), Chief Justice and Governor of Pennsylvania
- John McKinly (1721–1796), General Assembly and President of Delaware
- Marshall Kirk McKusick (born 1954), computer scientist
- Louis McLane (1786–1857), U.S. Representative from Delaware and U.S. Secretary of the Treasury
- Richard C. McMullen (1868–1944), manufacturer and Governor of Delaware
- Charles R. Miller (1857–1927), General Assembly and Governor of Delaware
- Thomas W. Miller (1886–1973), lawyer and U.S. Representative from Delaware
- Henry Milligan (born 1958) Amateur Athletic Union Heavyweight boxing Champion in1983
- John J. Milligan (1795–1875), lawyer snd U.S. Representative from Delaware
- Ruth Ann Minner (born 1935), Lieutenant Governor and Governor of Delaware
- Nathaniel Mitchell (1753–1815), Continental Congressman and Governor of Delaware
- Henry Molleston (1762–1819), General Assembly and elected Governor of Delaware
- Jacob Moore, Attorney General of Delaware
- Hugh M. Morris, federal judge
Read more about this topic: List Of People From Delaware