text: Robert C. McFarlane – National Security Advisor to President Ronald Reagan; known for his role in Iran–Contra
  Tug McGraw – Major League relief pitcher and two-time World Series winner
  Paul F. McHale Jr. – U.S. Congressman from Pennsylvania (D), Assistant Secretary of Defense for Homeland Defense
  Ed McMahon – television personality
  Walter Stauffer McIlhenny – served as president of McIlhenny Company, maker of Tabasco brand pepper sauce.
  Sid McMath – Governor of Arkansas
  Steve McQueen – Academy Award-nominated actor who also served in the U.S. Merchant Marine during World War II (Bullitt)
  William McMillan – Olympic gold medalist (1960), 25 meter rapid fire pistol
  Donald E. McQuinn – author of military and science fiction
  Zell Miller – Governor of Georgia, U.S. Senator (D)
  Billy Mills – Olympic gold medalist (1964), 10,000m run
  Tom Monaghan – founder of Domino's Pizza
  Lawrence Montaigne – actor and stuntman (The Great Escape, Star Trek)
  Elizabeth Moon – award-winning fantasy and science fiction author
  Alvy Moore – actor (Green Acres)
  Paul Moore Jr. – 13th Bishop of New York
  Jim E. Mora – NFL head football coach
  Robert S. Mueller III – former director of the FBI (2001-2013)
  Blackjack Mulligan (a.k.a. Robert Windham) – retired professional wrestler
  Robert Mulligan – Academy Award-nominated filmmaker (To Kill a Mockingbird, Summer of '42)