- Mascari, Mary (fl. 2010s) (stories)
- See marymascari.wordpress.com
- Maschwitz, (Albert) Eric (1901-1969) (stories) (assoc.)
- Born in Birmingham; educated at Cambridge; Director of Variety for the BBC; playwright.
- Masello, Robert (fl. 1970s-2010s) (stories) (assoc.)
- See www.robertmasello.com
- Masero, Tony (fl. 1970s-2010s) (stories) (art) (assoc.)
- See www.artnillustration.com
- Masini, Donna (1954- ) (stories)
- Professor of creative writing at Hunter College.
- Maskelyne, Nevil (1863-1924) (stories) (assoc.)
- See en.wikipedia.org/wiki/Nevil_Maskelyne_(magician)
- Maslin, Janet (R.) (1949- ) (stories) (assoc.)
- See en.wikipedia.org/wiki/Janet_Maslin
- Mason, Arthur (1876-1955) (stories)
- Born in Ireland; master of sailing ship; Superintendent of Ship Rigging for Submarine Boat Corporation in WWI; miner and prospector in U.S., Alaska, Australia and South America.
- Mason, Bobbie Ann (1940- ) (stories)
- See en.wikipedia.org/wiki/Bobbie_Ann_Mason
- Mason, Caroline Atwater [Mrs. John H. Mason] (1853-1939) (stories)
- Born in Providence, R.I.
- Mason, Colin (Victor James) (1926- ) (stories)
- See www.sf-encyclopedia.com/entry/mason_colin
- Mason, Daniel ({c}1976- ) (stories) (assoc.)
- See en.wikipedia.org/wiki/Daniel_Mason
- Mason, David [i.e., Samuel Mason] (1924-1974) (stories) (assoc.)
- See www.sf-encyclopedia.com/entry/mason_david
- Mason, David (1954- ) (stories)
- See www.poetryfoundation.org/bio/david-mason
- Mason, Douglas R(ankine) (1918-2013) (stories) (assoc.)
- See www.sf-encyclopedia.com/entry/mason_douglas_r
- Mason, Elmer Brown (1877-1955) (stories)
- See pulpflakes.blogspot.com/2012/10/ElmerBMason.html
- Mason, Frank H(enry Algernon) (1876-1965) (stories) (art)
- See www.askart.com/artist/Frank_Henry_Algernon_Mason/11116932/Frank_Henry_Algernon_Mason.aspx
- Mason, Grace Sartwell [i.e., Grace Sartwell Mason Howes] (1876-1966) (stories)
- Born and died in McKean County, Pennsylvania.
- Mason, Gregory (1889-1968) (stories) (assoc.)
- See www.sf-encyclopedia.com/entry/mason_gregory
- Mason, Jamie (fl. 2000s-2010s) (stories)
- See www.jamie-mason.com
- Mason, Lisa (Susan) (1953- ) (stories) (assoc.)
- See www.sf-encyclopedia.com/entry/mason_lisa
- Mason, Michael Henry (1900-1982) (stories)
- Born in Carnbee, Fife; educated at Eton and Sandhurst; landed proprietor and explorer.
- Mason, Rena (fl. 2010s) (stories) (assoc.)
- See www.renamasonwrites.com
- Mason, [Sir] Richard ({c}1633-1685) (stories)
- See en.wikipedia.org/wiki/Richard_Mason_(politician)
- Mason, Robert C(averly) (1942- ) (stories) (assoc.)
- See www.sf-encyclopedia.com/entry/mason_robert_c
- Mason, (Francis) Van Wyck (1901-1978) (stories) (assoc.)
- Mystery writer. Born in Boston, Massachusetts; died in Bermuda.
- Mason-Black, Jennifer (fl. 2010s) (stories)
- See www.jennifermasonblack.com
- Massa, Kyle (fl. 2010s) (stories)
- See kyleamassa.com
- Masselink, Ben (1919-2000) (stories) (assoc.)
- See articles.latimes.com/2000/jan/16/local/me-54589
- Massey, Christopher (1880-1964) (stories)
- Born in London; novelist and literary advisor to Sampson Low, Publishers.
- Massey, Claire (1981- ) (stories)
- See nightjarpress.weebly.com/claire-massey.html
- Massey, [Sir] Harrie (Stewart Wilson) (1908-1983) (stories)
- See en.wikipedia.org/wiki/Harrie_Massey
- Massey, Ilona [born Ilona Hajmássy] (1910-1974) (stories) (assoc.)
- See en.wikipedia.org/wiki/Ilona_Massey
- Massey, Raymond (Hart) (1896-1983) (stories)
- See en.wikipedia.org/wiki/Raymond_Massey
- Massey, Sujata (Banerjee) (1964- ) (stories) (assoc.)
- Born in England; was feature reporter for Baltimore Sun; also lived in Japan before returning to Baltimore.
- Massie, Robert K(inloch, III) (1929- ) (stories)
- See en.wikipedia.org/wiki/Robert_K._Massie
- Massingham, H(arold) J(ohn) (1888-1952) (stories)
- See en.wikipedia.org/wiki/H._J._Massingham
- Masson, David (Mather) (1822-1907) (stories) (assoc.)
- See en.wikipedia.org/wiki/David_Masson
- Masson, David I(rvine) (1915-2007) (stories)
- See www.sf-encyclopedia.com/entry/masson_david_i
- Masson, Madeleine [born Madeleine Levy] (1912-2007) (stories)
- See en.wikipedia.org/wiki/Madeleine_Masson
- Masson, Thomas L(ansing) (1866-1934) (stories)
- See en.wikipedia.org/wiki/Thomas_Lansing_Masson
- Masterman, Margaret [i.e., Margaret Mary Masterman Braithwaite] (1910-1986) (stories)
- Born in London; educated in Paris and at Cambridge, where she founded and directed the Cambridge Language Research Unit, which did research on machine translation and computational linguistics.
- Masterman, Walter S(idney) (1876-1946) (stories)
- See www.sf-encyclopedia.com/entry/masterman_walter_s
- Masters, Anthony (1940-2003) (stories)
- See www.sf-encyclopedia.com/entry/masters_anthony
- Masters, David; pseudonym of Charles Edwin Brand (1883-1965) (stories)
- See bearalley.blogspot.co.uk/2009/12/david-masters.html
- Masters, Dexter (Wright) (1908-1989) (stories)
- See www.sf-encyclopedia.com/entry/masters_dexter
- Masters, Edgar Lee (1869-1950) (stories) (assoc.)
- See en.wikipedia.org/wiki/Edgar_Lee_Masters
- Masters, F(rank) B(ird) (1873-1955) (art)
- See www.askart.com/artist/Frank_Bird_Masters/60240/Frank_Bird_Masters.aspx
- Masters, John (1914-1983) (stories) (assoc.)
- See en.wikipedia.org/wiki/John_Masters
- Masters, Priscilla (1952- ) (stories) (assoc.)
- Born in Halifax, Yorkshire, the third of seven multiracial children adopted by an orthopedic surgeon and his wife; brought up in Wales; trained as a nurse in Birmingham.
- Mastrantone, S. R. (fl. 2010s) (stories)
- See thewrittenabsurd.blogspot.co.uk
- Masud, Naiyer (1936-2017) (stories) (assoc.)
- See en.wikipedia.org/wiki/Naiyer_Masud
- Masur, Harold Q. (1909-2005) (stories) (assoc.)
- See en.wikipedia.org/wiki/Harold_Q._Masur
- Mata Hari [i.e., Margaretha Geertruida MacLeod (née Zelle)] (1876-1917) (stories) (assoc.)
- See en.wikipedia.org/wiki/Mata_Hari
- Matei, Liviu (fl. 2010s) (art)
- See liviumatei.carbonmade.com
- Mather, Berkely; pseudonym of John Evan Weston Davies (1909-1996) (stories) (assoc.)
- See en.wikipedia.org/wiki/Berkely_Mather
- Mather, Cotton (1663-1728) (stories)
- See en.wikipedia.org/wiki/Cotton_Mather
- Mather, Frank Jewett, Jr. (1868-1953) (stories)
- Born in Connecticut; educated at Johns Hopkins; director of a university museum; magazine editor; lived in N.J.
- Mather, Victoria (fl. 2010s) (stories) (assoc.)
- See vickymather.co.uk
- Mathers, E(dward) Powys (1892-1939) (stories)
- Born in London; educated at Oxford; newpaperman and author.
- Mathers, Helen; pseudonym of Ellen Mathews (1853-1920) (stories) (assoc.)
- See www.sf-encyclopedia.com/entry/mathers_helen
- Mathers, James (1936-2014) (stories)
- See www.imdb.com/name/nm0558483
- Mathers, (Edward) Powys (1892-1939) (stories)
- See en.wikipedia.org/wiki/Edward_Powys_Mathers
- Mathes, Harry (aaron) (1882-1969) (art)
- See www.askart.com/artist/Harry_A_Mathes/76095/Harry_A_Mathes.aspx
- Mathes, (Charles) Hodge (1879-1951) (stories)
- See archives.etsu.edu/?p=collections/findingaid&id=539&q=&rootcontentid=102873
- Mathes, Steven (fl. 2000s-2010s) (stories)
- See stevenmathes.com
- Matheson, Michael (fl. 2010s) (stories)
- See michaelmatheson.wordpress.com
- Matheson, Richard (Burton) (1926-2013) (stories) (assoc.)
- See www.sf-encyclopedia.com/entry/matheson_richard
- Matheson, Richard Christian (1953- ) (stories) (assoc.)
- See www.sf-encyclopedia.com/entry/matheson_richard_christian
- Matheus, John F(rederick) (1887-1983) (stories)
- See en.wikipedia.org/wiki/John_F._Matheus
- Mathew, Theobald (1866-1939) (stories)
- See archive.thetablet.co.uk/article/24th-june-1939/25/mr-theobald-mathew-we-much-regret-to-announce-the-
- Mathews, Ellen (Buckingham) (1853-1920) (stories)
- Born in Somerset.
- Mathews, Frances Aymar (1865-1925) (stories)
- Born in New York City.
- Mathews, John L(athrop) (1874-1916) (stories)
- Journalist and author. Born in Evanston, Illinois; died in Normandie, Missouri.
- Mathews, Julia A. ({c}1838-1881) (stories)
- See readseries.com/auth-dm/mathews-bio.htm
- Mathewson, Christy (1880-1925) (stories) (assoc.)
- Pitcher for the NY Giants.
- Mathijsen, Django (fl. 2010s) (stories)
- See www.djangomathijsen.nl
- Mathis, June [born June Beulah Hughes] (1887-1927) (stories)
- See en.wikipedia.org/wiki/June_Mathis
- Mathison, Volney G. (1897-1965) (stories)
- See www.sf-encyclopedia.com/entry/mathison_volney_g
- Matson, Norman (Haghejm) (1893-1965) (stories) (assoc.)
- See www.sf-encyclopedia.com/entry/matson_norman
- Matsuoka, Yoko (fl. 2010s) (stories) (art) (assoc.)
- See www.m-y-designs.com
- Matsuoka, Yōsuke (1880-1946) (stories)
- See en.wikipedia.org/wiki/Y%C5%8Dsuke_Matsuoka
- Matsuura, Thersa (fl. 2010s) (stories)
- See www.thersamatsuura.com
- Matter, John (1883-1949) (stories)
- Indiana author; died in Illinois.
- Matters, Leonard (Warburton) (1881-1951) (stories)
- Journalist, novelist, London representative of The Hindu Newspaper. Born in Adelaide, Australia; died in Much Haddam, England.
- Matteson, H(erman) H(oward) (1876-1951) (stories)
- Author, ships surgeon, surgeon to Central American explorers and inmates in federal penitentaries; radio broadcaster. Born in Grundy County, Illinois; lived in Los Angeles, California.
- Matthewman, Sydney (1902-1970) (stories) (assoc.)
- See desturmobed.blogspot.co.uk/2012/06/s-matthewman.html
- Matthews, Adelaide (1876-1958) (stories)
- Born in Kenduskeag, Maine; died in New York City; actress, then playwright.
- Matthews, (James) Brander (1852-1929) (stories) (assoc.)
- See en.wikipedia.org/wiki/Brander_Matthews
- Matthews, Jack [i.e., John Harold Matthews, Jr.] (1925-2013) (stories)
- See en.wikipedia.org/wiki/Jack_Matthews_(author)
- Matthews, Jason (fl. 2010s) (stories)
- See pages.simonandschuster.com/redsparrow/meetjason
- Matthews, Patricia (Anne Klein, née Ernst) (1927-2006) (stories) (assoc.)
- See en.wikipedia.org/wiki/Patricia_Matthews
- Matthews, Walter (1881-1973) (stories)
- See en.wikipedia.org/wiki/Walter_Matthews_(priest)
- Matthey, Cécile (1973- ) (art)
- See www.caeciliana.ch
- Matthison, Edith Wynne (1875-1955) (stories) (assoc.)
- See en.wikipedia.org/wiki/Edith_Wynne_Matthison
- Mattila, D(eborah) L. (fl. 2010s) (stories)
- See www.pw.org/content/deborah_l_mattila
- Mattson, George; pseudonym (fl. 1960s) (stories)
- Unresolved pseudonym, perhaps for Leo Heiman. Not martial arts expert George Edward Mattson (1937- ).