| Iacobeni | Iacobeni | Romania, Iacobeni | -- | -- | | | |
| Interzona | Interzona | Italy, Verona, Via Santa Teresa, 6 | 1999-10-07 | -- | 1999 | 1 | |
| Innsjön | Innsjön | Sweden, Innsjön | 1911-07-03 | 1911-07-04 | 1911 | 1 | |
| Innsbrucker Kellertheater | Innsbrucker Kellertheater | Austria, Innsbruck, Adolf-Pichler-Platz 8 | 2004-10-20 | 2004-11-30 | 2004 | 1 | |
| International House Theater | International House Theater | United States, Chicago | 1934-03-16 | 1934-03-17 | 1934 | 1 | |
| Iran | Iran | Iran, Iran | 1993-02-03 | -- | 1993–2017 | 3 | |
| Ingatestone Hall | Ingatestone Hall | England, Essex, Hall Ln | 2007-09-21 | 2021-07-02 | 2007–2021 | 3 | |
| Irazee | Irazee | United States, Irazee | -- | -- | | | |
| Ismailia Culture Palace Theatre | Ismailia Culture Palace Theatre | Egypt, Ismaïlia | 2006-08-22 | -- | 2006 | 1 | |
| Intimes Theater | Intimes Theater | Germany, Nürnberg, Wolfsschlucht | 1901-01-03 | -- | 1901–1912 | 7 | |
| Imperial Theatre | Imperial Theatre | United States, New York, 249 W 45th St | 1924-05-01 | -- | 1924 | 1 | |
| Isbjørnhallen | Isbjørnhallen | Norway, Hammerfest, Meridiangata 8 | 1997-11-05 | 1997-11-06 | 1997 | 1 | |
| Iranshahr | Iranshahr | Iran, Tehran, Artists' Park, Iranshahr St. | 2020-02-16 | 2020-03-16 | 2020 | 1 | |
| İş Sanat Kültür Merkezi | İş Sanat Kültür Merkezi | Turkey, Levent/İstanbul, İş Kuleleri, Büyükdere Cd., | 2010-02-28 | 2010-05-16 | 2010 | 1 | |
| Istindportalen | Istindportalen | Norway, Heggelia, Kapellveien 2 | 2007-03-12 | -- | 2007 | 1 | |
| Il Torrione | Il Torrione | Italy, Città di Castello, via Gramsci 28 | 2011-06-23 | -- | 2011 | 1 | |
| Ianca | Ianca | Romania, Ianca | -- | -- | | | |
| Iberoamericano de Teatro de Bogotá | Iberoamericano de Teatro de Bogotá | Colombia, Bogotá, Cundinamarca, Carrera 19 # 37-53 | 2008-03-07 | 2008-03-10 | 2008 | 1 | |
| Ibestad Samfunnshus | Ibestad Samfunnshus | Norway, Hamnvik, 9450 Hamnvik | 1970-02-28 | -- | 1970 | 1 | |
| Ishøj Centersal | Ishøj Centersal | Denmark, Ishøj | 2002-11-15 | -- | 2002–2004 | 2 | |
| Islington | Islington | England, London | -- | -- | | | |
| IATC Studio Cassandra | IATC Studio Cassandra | Romania, Bucharest, Str. Matei Voievod nr. 75-77 | 1957-03-15 | -- | 1957–1985 | 4 | |
| Instituto Andrés Soler (ANDA) | Instituto Andrés Soler (ANDA) | Mexico, Mexico City, Petén 45, Narvarte Poniente | 2000-10-14 | -- | 2000 | 1 | |
| Immenstadt | Immenstadt | Germany, Immenstadt | -- | -- | | | |
| Ivano-Frankivsk | Ivano-Frankivsk | Ukraine, Ivano-Frankivsk | 1907-03- | 1907-04- | 1907 | 1 | |
| Interimstheater Brünn | Interimstheater Brünn | Czech Republic, Brno, Žerotín square | 1880-01-01 | -- | 1880 | 1 | |
| Illinois Theatre | Illinois Theatre | United States, Rock Island | 1904-03-15 | 1904-03-15 | 1904 | 1 | |
| Ibsengården | Ibsengården | Norway, Skien, Snipetorp | 2001-08-23 | 2004-08-26 | 2001–2004 | 2 | |
| Île-Saint-Louis-Paul Rey, Théâtre de l' | Théâtre de l'Île-Saint-Louis-Paul Rey | France, Paris, 39 quai d'Anjou | 2009-04-21 | 2009-05-24 | 2009 | 1 | |
| Istropolitana MDPOH | Istropolitana MDPOH | Slovak Republic, Bratislava, Ventúrska 3 | 2012-06-26 | -- | 2012 | 1 | |
| Intimiteatteri | Intimiteatteri | Finland, Helsinki | 1951-03-28 | -- | 1951–1962 | 3 | |
| Intimní scéna | Intimní scéna | Czech Republic, Tábor | 1924-12-18 | -- | 1924 | 1 | |
| Intima Teatern | Intima Teatern | Sweden, Stockholm, Barnhusgatan 20 | 1912-11-01 | 1919-03-14 | 1912–1919 | 3 | |
| Il Piccolo Teatro Instabile | Il Piccolo Teatro Instabile | Italy, Turin, via Garessio 18 | 2004-04-24 | -- | 2004 | 1 | |
| Ithaca College Little Theatre | Ithaca College Little Theatre | United States, Ithaca, Ithaca College | 1952-02-28 | 1952-03-01 | 1952 | 1 | |
| Istanbul | Istanbul | Turkey, Istanbul | 1900-12- | 2014-05-29 | 1900–2014 | 5 | |
| Impossible Ragtime Theater | Impossible Ragtime Theater | United States, New York | 1979-01-28 | -- | 1979 | 1 | |
| Ipswich | Ipswich | England, Ipswich | -- | -- | | | |
| Islamabad | Islamabad | Pakistan, Islamabad | 2006-05-17 | -- | 2006 | 1 | |
| Ireland | Ireland | Ireland | 1980-01-29 | 1980-04-19 | 1980 | 1 | |
| Innsbruck | Innsbruck | Austria, Innsbruck | 1946-04-27 | 1946-04-28 | 1946 | 1 | |
| Idrettshallen | Idrettshallen | Norway, Kautokeino | 1997-10-31 | -- | 1997 | 1 | |
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