| Imperial Theatre | Imperial Theatre | England, Westminster, London, Tothill Street | 1903-01-25 | 1903-01-26 | 1903 | 2 | |
| Impossible Ragtime Theater | Impossible Ragtime Theater | United States of America, New York | 1979-01-28 | -- | 1979 | 1 | |
| Incognito Theatre | Incognito Theatre | England, Friern Barnet, London, Holly Park Road | 2005-02-08 | 2012-12-01 | 2005–2012 | 2 | |
| Independent Theatre | Independent Theatre | Australia, North Sydney, 271 Miller Street | 1946-10-10 | -- | 1946–1951 | 2 | |
| Inderøy kulturhus | Inderøy kulturhus | Norway, Inderøy, Vennalivegen 15 | 2001-06-25 | -- | 2001–2006 | 2 | |
| Inderøy Kulturhus | Inderøy Kulturhus | Norway, Sakshaug | 1993-03-11 | -- | 1993 | 1 | |
| India | India | India | 1940-- | -- | 1940–2020 | 4 | |
| Indiana Repertory Theatre | Indiana Repertory Theatre | United States of America, Indianapolis, 140 W. Washington Street | 2001-01-09 | 2001-02-03 | 2001 | 1 | |
| Industrial space | Industrial Space | United States of America, New York, Chelsea | 1994-08- | 1995-11- | 1994 | 2 | |
| Industrial Strength Theatre | Industrial Strength Theatre | United States of America, Herndon, 269 Sunset Park Dr | 2008-01-25 | 2008-02-16 | 2008 | 1 | |
| Ineu | Ineu | Romania, Ineu | -- | -- | | | |
| Ingatestone Hall | Ingatestone Hall | England, Essex, Hall Ln | 2007-09-21 | 2021-07-02 | 2007–2021 | 3 | |
| Ingeborg-Drewitz-Bibliothek | Ingeborg-Drewitz-Bibliothek | Germany | 2023-08-31 | 2023-08-31 | 2023 | 1 | |
| Ingebrigt Davik-huset | Ingebrigt Davik-huset | Norway, Brattvåg, Bernt Hildrevegen 2 | 2011-04-28 | 2014-04-01 | 2011–2014 | 2 | |
| Ingensteds | Ingensteds | Norway, Oslo, Brenneriveien 9 | 2014-12-14 | -- | 2014 | 1 | |
| Inkonst | Inkonst | Sweden, Malmö, Bergsgatan 29 | 2006-09-29 | 2006-10-01 | 2006 | 1 | |
| Inner Stage, The, University of Guelph | The Inner Stage, University of Guelph | Canada, Guelph, 50 Stone Road East | 1990-11-25 | 1990-12-01 | 1990 | 1 | |
| Innsbruck | Innsbruck | Austria, Innsbruck | 1946-04-27 | 1946-04-28 | 1946 | 1 | |
| Innsbrucker Kellertheater | Innsbrucker Kellertheater | Austria, Innsbruck, Adolf-Pichler-Platz 8 | 2004-10-20 | 2004-11-30 | 2004 | 1 | |
| Innsjön | Innsjön | Sweden, Innsjön | 1911-07-03 | 1911-07-04 | 1911 | 1 | |
| Inntunet | Inntunet | Norway, Vinstra, Vinstra | 2006-08-07 | -- | 2006 | 1 | |
| Institut Méditerranéen des Métiers du Spectacle - IMMS | Institut Méditerranéen des Métiers du Spectacle - IMMS | France, Marseille, 41 rue Jobin | 2017-04-11 | 2017-04-15 | 2017 | 1 | |
| Institut Papa Gueye Fall | Institut Papa Gueye Fall | Senegal, Dakar | 2021-05-19 | -- | 2021 | 1 | |
| Institute of Contemporary Arts | Institute of Contemporary Arts | England, London, The Mall | 1995-07-04 | 1995-07-08 | 1995 | 1 | |
| Instituto Andrés Soler (ANDA) | Instituto Andrés Soler (ANDA) | Mexico, Mexico City, Petén 45, Narvarte Poniente | 2000-10-14 | -- | 2000 | 1 | |
| Instituto LING | Instituto LING | Brazil, Porto Alegre, R. João Caetano, 440 | 2018-05-17 | 2018-05-26 | 2018 | 1 | |
| Instituto Municipal de Educación | Instituto Municipal de Educación | Spain, Madrid, Calle de Mejía Lequerica, 21 | 1963-10-27 | -- | 1963 | 1 | |
| Instituto Português do Desporto e da Juventude | Instituto Português do Desporto e da Juventude | Portugal, Lisbon | 2023-06-05 | 2023-06-05 | 2023 | 1 | |
| Interimstheater Brünn | Interimstheater Brünn | Czech Republic, Brno, Žerotín square | 1880-01-01 | -- | 1880 | 1 | |
| International Festival of Monodrama | International Festival of Monodrama | Ukraine, Kiev | 2006-09-23 | -- | 2006 | 1 | |
| International Festival of Monodrama - Die Pumpe | International Festival of Monodrama - Die Pumpe | Germany, Kiel | 2006-11-11 | -- | 2006 | 1 | |
| International House Theater | International House Theater | United States of America, Chicago | 1934-03-16 | 1934-03-17 | 1934 | 1 | |
| International Theatre | International Theatre | United States of America, New York | 1946-11-12 | 1947-02-19 | 1946 | 1 | |
| International Theatre of Tehran | International Theatre of Tehran | Iran, Tehran | 1970-- | -- | 1970 | 1 | |
| Interzona | Interzona | Italy, Verona, Via Santa Teresa, 6 | 1999-10-07 | -- | 1999 | 1 | |
| Intima Teatern | Intima Teatern | Sweden, Stockholm, Barnhusgatan 20 | 1912-11-01 | 1919-03-14 | 1912–1919 | 3 | |
| Intiman Theatre | Intiman Theatre | United States of America, Seattle, 201 Mercer Street | 1996-12-08 | 2012-08-25 | 1996–2012 | 4 | |
| Intimes Theater | Intimes Theater | Germany, Nürnberg, Wolfsschlucht | 1901-01-03 | -- | 1901–1912 | 7 | |
| Intimes Theater | Intimes Theater | Switzerland, Bern | 1909-10-21 | 1909-12-01 | 1909 | 1 | |
| Intimiteatteri | Intimiteatteri | Finland, Helsinki, Ratakatu 9 | 1951-03-28 | -- | 1951–1962 | 3 | |
| Intimní scéna | Intimní scéna | Czech Republic, Tábor | 1924-12-18 | -- | 1924 | 1 | |
| IOGT-huset | IOGT-huset | Norway, Bergen, Sverresgate 1 | 1990-02-08 | 1990-02-14 | 1990 | 1 | |
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