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- Maestrazgo: Hispanic kingdom in the José Juan Carrión´s Blog de Heráldica.
- Magyaristan: Islamic state in the former Hungary. From the alternate history book The Years of Rice and Salt by Kim Stanley Robinson.
- Margoth: European kingdom in Edgar Rice Burroughs's The Rider.
- Marisi: appears in Rex Stout's A Prize for Princes ("Ruritanian romance" set in Fasilica and Marisi; serialized in 1914 and reprinted as a book in the 1990s; author is the later creator of the Nero Wolfe mystery series).
- Marshovia (Marsovia, Makovnia): small Eastern European kingdom most likely located somewhere near Transylvania in the operetta The Merry Widow.
- Masavania, Kosnia: European kingdoms in the movie If I Were Queen.
- Mendorra: principality located near Germany from the American soap opera, One Life to Live.
- Mervo: island principality in The Prince and Betty by P. G. Wodehouse
- Messina: principality in Richard Harding Davis's, The King's Jackal (1891).
- Mittenheim: grand duchy in The Heart of Princess Osra by Anthony Hope
- Mixo-Lydia: Balkan country in the novels of Angela Thirkell; has a long-standing enmity with neighbouring Slavo-Lydia.
- Moldavia: Eastern European country from Dynasty TV series (note: Moldavia really exists as a nation itself and also as a region in Romania).
- Moldovakia: Eastern European country in Recess best known for its spies and its luge team.
- Molvanîa: Eastern European country from a parody travel guidebook; from the same authors as Phaic Tăn and San Sombrèro.
- Moronica: parody of Nazi Germany from the Three Stooges short You Nazty Spy.
- Mypos: Native home of Balki Bartokomous on Perfect Strangers.
Read more about this topic: List Of Fictional European Countries