| Abbey Theatre | Abbey Theatre | 2005 – 2023 | 4 | 1 |
| Abilene Christian University Department of Theatre | Abilene Christian University Department of Theatre | 2002 | 1 | |
| Accademia del Teatro di Firenze | Accademia del Teatro di Firenze | 1992 – 2016 | 224 | 14 |
| Accademia Nazionale D'Arte Drammatica | Accademia Nazionale D'Arte Drammatica | 2024 | 2 | 1 |
| Acting Company Mito Theatre | Acting Company Mito Theatre | 1993 | 1 | |
| Actors Company, The | The Actors Company | 1996 – 2003 | 3 | |
| Actors from Christiania Theater | Actors from Christiania Theater | 1867 | 1 | |
| Adelaide Festival of Arts | Adelaide Festival of Arts | 2006 | 1 | |
| Adelaide Repertory Theatre Incorporated | Adelaide Repertory Theatre Incorporated | 1917 – 1964 | 3 | |
| Adelaide University Theatre Guild | Adelaide University Theatre Guild | 1960 – 1986 | 5 | |
| Aesthetic Realism Theatre Company, The | The Aesthetic Realism Theatre Company | 2001 | 2 | |
| Afternoon Theatre, The | The Afternoon Theatre | 1909 | 2 | |
| AGADU | AGADU | 1999 | 1 | |
| Agder Teater | Agder Teater | 1993 – 2015 | 70 | 7 |
| Agnes Sorma Ensemble | Agnes Sorma Ensemble | 1900 | 11 | |
| Agnes Sorma und die Irving Place Theatergesellschaft, N.Y. | Agnes Sorma und die Irving Place Theatergesellschaft, N.Y. | 1898 | 1 | |
| Agnes Straub | Agnes Straub | 1935 | 1 | |
| Agrupació Avenir | Agrupació Avenir | 1905 | 1 | |
| Agrupació Peer Gynt | Agrupació Peer Gynt | 1908 | 2 | |
| Agrupament literari ‘Henrik Ibsen’ | Agrupament literari ‘Henrik Ibsen’ | 1904 | 1 | |
| Akademi for scenekunst | Akademi for scenekunst | 2006 – 2009 | 5 | |
| Akademičeskij dramatičeskij teatr im. V. F. Komissarževskoj | Akademičeskij dramatičeskij teatr im. V. F. Komissarževskoj (Komissarzhevskaya Theatre) | 2016 | 1 | |
| Akademičeskij Maly dramatičeskij teatr – Teatr Evropy | Akademičeskij Maly dramatičeskij teatr – Teatr Evropy (Academic Maly Drama Theatre – Theatre of Europe) | 2011 | 1 | |
| Akademisch-Dramatischer Verein | Akademisch-Dramatischer Verein (Akademische-Dramatische Verein) | 1893 | 4 | |
| Akademischer Studentenverein | Akademischer Studentenverein | 1896 | 1 | |
| Akademischer Verein für Kunst und Litteratur | Akademischer Verein für Kunst und Literatur (Akademischer Verein für Kunst und Litteratur) | 1902 | 1 | |
| Akosha | Akosha | 1976 | 3 | |
| Akroama | Akroama | 2019 – 2023 | 27 | 3 |
| Albert Ranfts dramatiska turné | Albert Ranfts dramatiska turné | 1919 | 1 | |
| Albert Ranfts Sällskap | Albert Ranfts Sällskap | 1885 – 1900 | 21 | |
| Albert u. Else Bassermann | Albert u. Else Bassermann | 1933 – 1950 | 13 | |
| Alexander Moissi | Alexander Moissi | 1933 | 2 | |
| Alfredo B. Crevenna | Alfredo B. Crevenna | 1954 | 2 | |
| Alireza Kooshk Jalali's Company | Alireza Kooshk Jalali's Company (Alireza Kooshk Jalali?s Company) | 2010 | 1 | |
| Allan Holubar | Allan Holubar | 1915 | 1 | |
| Almeida Theatre Company, The | The Almeida Theatre Company | 1990 – 2018 | 5 | |
| Amanti del Teatro Neretino | Amanti del Teatro Neretino | 2024 | 1 | |
| Amatørteatret | Amatørteatret | | | |
| Ambasciata Norvegese in Italia | Ambasciata Norvegese in Italia | 2020 | 1 | |
| American Academy of Dramatic Arts | American Academy of Dramatic Arts | 1907 | 2 | |
| American Conservatory Theater | American Conservatory Theater | 1973 – 2007 | 8 | |
| American Ibsen Theater | American Ibsen Theater | 1983 – 1985 | 6 | |
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