| Ireland Drama Festival | Ireland Drama Festival | | | |
| Isac Fredrik Smitts sällskap | Isac Fredrik Smitts sällskap | 1877 – 1880 | 12 | |
| Independent Theatre Society, The | The Independent Theatre Society | 1891 – 1997 | 14 | |
| Independent Company, The | The Independent Company | 1899 | 1 | |
| I Nea Skini (Konstantinos Christomanos) | I Nea Skini (Konstantinos Christomanos) | 1901 – 1904 | 13 | |
| Ibsen-Theater aus Berlin, Das | Das Ibsen-Theater aus Berlin | 1901 – 1912 | 60 | |
| internationale Tournée Gustav Lindemann, Die | Die internationale Tournée Gustav Lindemann | 1903 – 1904 | 13 | |
| Ida Aalberg-Tournéen | Ida Aalberg-Tournéen | 1904 | 13 | |
| Internationale Tournee Maria Rehoff | Internationale Tournee Maria Rehoff | 1904 – 1912 | 85 | |
| Incorporated Stage Society | Incorporated Stage Society | 1906 | 1 | |
| Ibsen-Ensemble , Das | Das Ibsen-Ensemble | 1906 | 42 | |
| Intimes Theater | Intimes Theater | 1909 | 1 | |
| Ibsen Club, The | The Ibsen Club | 1910 – 1911 | 5 | |
| Irving Place Company | Irving Place Company | 1917 | 1 | |
| Ibsenjubileet (Ibsen Anniversary) | Ibsenjubileet (Ibsen Anniversary) | 1928 | 1 | |
| Ibsen Society, The | The Ibsen Society | 1930 | 2 | |
| Independent Theatre, The | Independent Theatre (The Independent Theatre) | 1946 – 2023 | 2 | |
| Illini Theatre Guild Laboratory Theatre, The | The Illini Theatre Guild Laboratory Theatre | 1947 – 1949 | 4 | |
| Internationale Maifestspiele | Internationale Maifestspiele | 1954 – 2003 | 3 | |
| Indiana University Department of Theatre and Drama | Indiana University Department of Theatre and Drama | 1979 – 2019 | 3 | |
| Il Mezzogiorno Nuovo D'Italia | Il Mezzogiorno Nuovo D'Italia | 1984 | 1 | 1 |
| ITESM Unidad Chihuahua | ITESM Unidad Chihuahua | 1985 | 1 | |
| Illinois Repertory Theatre University of Illinois | Illinois Repertory Theatre University of Illinois | 1988 | 1 | |
| Ibseniana-festivalen | Ibseniana-festivalen | 1989 – 2004 | 24 | |
| Ibsenfestivalen | Ibsenfestivalen (International Ibsen Festival) (Ibsenfestivalen) | 1990 – 2020 | 549 | 3 |
| Ibsen Festival Fringe | Ibsen Festival Fringe | 1992 | 1 | |
| Internasjonale Figurteaterfestival, Den | Den Internasjonale Figurteaterfestival | 1992 – 1993 | 1 | |
| Institutt for drama/film/teater | Institutt for drama/film/teater | 1994 | 1 | |
| Ibsen Performance Group | Ibsen Performance Group | 1998 – 2002 | 9 | |
| Interzona and La Biennale di Venezia | Interzona (Interzona and La Biennale di Venezia) | 1999 – 2000 | 6 | |
| Ibsen Kulturfestival | Ibsen Kulturfestival | 2001 | 1 | |
| Ibsen- og Hamsun-dagene 2003 | Ibsen- og Hamsun-dagene 2003 | 2003 | 1 | |
| Ibsenhuset og Grimstad bymuseum | Ibsenhuset og Grimstad bymuseum | 2003 – 2005 | 6 | |
| Ibsen- og Hamsun-dagene 2004 | Ibsen- og Hamsun-dagene 2004 | 2004 | 1 | |
| International Theatre Festival | International Theatre Festival | 2004 | 2 | |
| Ibsenforbundet | Ibsenforbundet | 2004 – 2007 | 61 | |
| Ibsen- og Hamsun-dagene 2005 | Ibsen- og Hamsun-dagene 2005 | 2005 | 2 | |
| Ibsen- og Hamsun-dagene 2006 | Ibsen- og Hamsun-dagene 2006 | 2005 – 2006 | 2 | |
| Ibsen og Hamsun for ungdom 2006 | Ibsen og Hamsun for ungdom 2006 | 2006 | 1 | |
| International Ibsen Conference, The | The International Ibsen Conference | 2006 | 1 | |
| Ibsenkvintetten | Ibsenkvintetten | 2006 | 1 | |
| Ibsen 2006 | Ibsen 2006 | 2006 | 1 | |
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