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- John Henry Mackay (1864–1933), Scottish-German author
- Bennett Madison (b. 1981), American author
- Gregory Maguire (b. 1954), American author, wrote Wicked: The Life and Times of the Wicked Witch of the West (1995)
- Klaus Mann (1906–1949), German author
- Thomas Mann (1875–1955), German author, wrote Death in Venice (1912)
- David Charles Manners (b. 1965), English author
- Jaime Manrique (b. 1949), Colombian-American author, wrote Latin Moon in Manhattan (1992), Eminent Maricones (1998)
- Abniel Marat (b. 1958), Puerto Rican author
- Jovette Marchessault (b. 1938), French-Canadian author, wrote Tryptique lesbienne (1980)
- Douglas A. Martin (b. 1973), American author
- Nemir Matos-Cintrón (b. 1949), Puerto Rican author and poet
- F.O. Matthiessen (1902–1950), American literary critic
- Glauco Mattoso (pseudonym of Pedro José Ferreira da Silva, b. 1951), Brazilian author
- W. Somerset Maugham (1874–1965), English playwright and author, wrote Of Human Bondage (1915)
- Armistead Maupin (b. 1944), American author, wrote Tales of the City (1978)
- Carson McCullers (1917–1967), American author, wrote Reflections in a Golden Eye (1941)
- William Manuel Mena-Santiago (1954-), Puerto Rican poet
- Terrence McNally (b. 1939), American playwright, wrote The Ritz (1975), Love! Valour! Compassion! (1994)
- Herman Melville (1819–1891), American author, wrote Moby-Dick (1851) and Billy Budd (1891)
- James Merrill (1926–1995), American poet
- Charlotte Mew (1869–1928), English author
- Michelangelo (1475–1564), Italian artist and poet
- Edna St. Vincent Millay (1892–1950), American poet
- Isabel Miller (pseudonym of Alma Routsong) (1924–1996), American author, wrote A Place for Us (1969)
- John Milton (1608–1674), English poet, author of Paradise Lost (1667) and Paradise Regained (1670)
- Yukio Mishima (1925–1970), Japanese author, wrote Confessions of a Mask (1949)
- Gabriela Mistral (pseudonym of Lucila Godoy Alcayaga, 1889–1957), Chilean poet, Nobel Prize winner
- Sylvia Molloy (b. 1938), Argentine author
- Paul Monette (1945–1995), American author, wrote Borrowed Time (1988)
- Carlos Monsiváis (b. 1938), Mexican author
- Carlos Montenegro (1900–1981), Cuban author
- Cherríe Moraga (b. 1952), Chicana author, wrote Loving in the War Years (1983)
- Ethan Mordden (b. 1949), American author
- César Moro (1903–1956), Peruvian poet
- Jimmy Mudge (1991–Present), American Poet, bad reviews.
- Manuel Mujica Láinez (1910–1984), Argentine author
- Miguel Elías Muñoz (b. 1954), Cuban-American author, wrote The Greatest Performance (1991)
- Mirjam Müntefering (b. 1969), German author
Read more about this topic: List Of LGBT Writers