| Maastrichts Theaterensemble Het Vervolg | Maastrichts Theaterensemble Het Vervolg | 1997 | 1 | |
| Münchner Kammerspiele (Schauspielhaus) | Münchner Kammerspiele (Schauspielhaus) | 1989 – 2023 | 10 | |
| Münchner Hoftheater-Ensemble | Münchner Hoftheater-Ensemble | 1912 | 1 | |
| Münchener Künstler-Theater | Münchener Künstler-Theater | 1914 | 1 | |
| Münchener Ensemble (Direktion: Emil Meßthaler) | Münchener Ensemble (Direktion: Emil Meßthaler) | 1893 | 6 | |
| Münchener Dramatische Gesellschaft | Münchener Dramatische Gesellschaft | 1900 | 2 | |
| Mutumbela Gogo | Mutumbela Gogo | 2006 – 2025 | 6 | |
| Musikk i Nordland | Musikk i Nordland | 2006 | 1 | |
| Musica Independent Theatre Group, La | La Musica Independent Theatre Group | 2009 – 2013 | 17 | |
| Museo Deseo | Museo Deseo | 2006 | 1 | |
| Munroe Park Theater Guild, The | The Munroe Park Theater Guild | 2001 | 1 | |
| Movimento Artistico I Birbanti | Movimento Artistico I Birbanti | 2015 | 1 | 1 |
| Mountain Empire Community Theatre, The | The Mountain Empire Community Theatre | 2007 | 1 | |
| Moskva Kunstnerteater | Moskva Kunstnerteater | 1905 | 3 | |
| Moskovskij Hudožestvennyj akademičeskij teatr | Moskovskij Hudožestvennyj akademičeskij teatr (Moscow Art Theatre) | 1900 – 1924 | 7 | |
| Mosaico Produções | Mosaico Produções (Mosaico Productions) | 2025 | 1 | |
| Morosco Company, The | The Morosco Company | 1904 | 3 | |
| Móricz Zsigmond Színház | Móricz Zsigmond Színház | 1995 | 2 | |
| Montreal Stage Society | Montreal Stage Society | 1918 | 1 | |
| Montgomery Theatre, The | The Montgomery Theatre | 2011 | 2 | |
| Monologtheater | Monologtheater | 2023 | 2 | |
| Molde Videregående skole | Molde Videregående skole | 2013 | 1 | |
| Mofeng she (Windmill Society) | Mofeng she (Windmill Society) | 1935 | 1 | |
| Modern Stage | Modern Stage | 1915 | 2 | |
| Mockingbird Theatre | Mockingbird Theatre | 2000 | 1 | |
| Moat Club, The | The Moat Club | 2007 | 7 | |
| Mme Vera F Komisarzhevskaya Repertory | Mme Vera F Komisarzhevskaya Repertory | 1908 | 1 | |
| Minkul'tury RF | Minkul'tury RF (Ministry of Culture of the Russian Federation) | 2022 | 1 | |
| Ministero della cultura (MiBACT) | Ministero della cultura (MiBACT) | 2024 – 2025 | 3 | |
| Ministério da Cultura | Ministério da Cultura | 2020 | 2 | |
| Mingei / Shochiku | Shochiku (Mingei / Shochiku) | 1986 | 1 | |
| Mingei (People's Theatre) | Mingei (People's Theatre) | 1953 – 2002 | 6 | |
| Milwaukee Repertory Theater Company | Milwaukee Repertory Theater Company | 1971 – 2004 | 3 | |
| milwaukee chamber theatre | Milwaukee Chamber Theatre | 2025 | 1 | |
| MIDI LIDI | MIDI LIDI | 2011 – 2012 | 3 | |
| Michael Grandage Company | Michael Grandage Company | 2025 | 1 | |
| MGA Productions Limited | MGA Productions Limited | 1939 | 1 | |
| Mezinárodní festival Divadlo | Mezinárodní festival Divadlo | 2007 | 1 | |
| Metropolitan Players, The | The Metropolitan Players | 1912 – 1913 | 3 | |
| Městské divadlo v Táboře | Městské divadlo v Táboře | 1924 | 1 | |
| Meßthaler-Ensemble vom Neuen Deutschen Theater München, Das | Das Meßthaler-Ensemble vom Neuen Deutschen Theater München | 1895 | 1 | |
| Melbourne Theatre Company | Melbourne Theatre Company | 1970 – 1998 | 15 | |
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