| Ibsenfestivalen | Ibsenfestivalen (International Ibsen Festival) (Ibsenfestivalen) | 1990 – 2020 | 549 | 3 |
| I Tarocchi - compagnia teatrale | I Tarocchi - compagnia teatrale | 2022 | 4 | 2 |
| Ile Flottante | Ile Flottante | 2013 – 2014 | 3 | 1 |
| Il Teatro della città | Teatro della città | 2019 | 1 | 1 |
| Il Picchio | Il Picchio | 2021 | 1 | 1 |
| Il Mezzogiorno Nuovo D'Italia | Il Mezzogiorno Nuovo D'Italia | 1984 | 1 | 1 |
| Internasjonale Figurteaterfestival, Den | Den Internasjonale Figurteaterfestival | 1992 – 1993 | 1 | |
| Ida Müller | Ida Müller | 2007 – 2012 | 8 | |
| Ibsen Festival Fringe | Ibsen Festival Fringe | 1992 | 1 | |
| International Ibsen | International Ibsen | 2010 | 1 | |
| Ibsen Club, The | The Ibsen Club | 1910 – 1911 | 5 | |
| Ibsen 2006 | Ibsen 2006 | 2006 | 1 | |
| Ibsen Scope | Ibsen Scope | 2019 – 2024 | 5 | |
| Ibsen-Ensemble , Das | Das Ibsen-Ensemble | 1906 | 42 | |
| Ibsen og Hamsun for ungdom 2006 | Ibsen og Hamsun for ungdom 2006 | 2006 | 1 | |
| Irving Place Company | Irving Place Company | 1917 | 1 | |
| International Ibsen Seminar and Theatre Festival | International Ibsen Seminar and Theatre Festival | 2009 – 2012 | 3 | |
| I Nea Skini (Konstantinos Christomanos) | I Nea Skini (Konstantinos Christomanos) | 1901 – 1904 | 13 | |
| Ibsen- og Hamsun-dagene 2004 | Ibsen- og Hamsun-dagene 2004 | 2004 | 1 | |
| Ibsen- og Hamsun-dagene 2011 | Ibsen- og Hamsun-dagene 2011 | 2011 | 1 | |
| Indiana University Department of Theatre and Drama | Indiana University Department of Theatre and Drama | 1979 – 2019 | 3 | |
| Intervención Ibsen | Intervención Ibsen | 2016 | 4 | |
| internationale Tournée Gustav Lindemann, Die | Die internationale Tournée Gustav Lindemann | 1903 – 1904 | 13 | |
| Ibsenhuset og Grimstad bymuseum | Ibsenhuset og Grimstad bymuseum | 2003 – 2005 | 6 | |
| Intercity Festival Oslo | Intercity Festival Oslo | 2009 | 1 | |
| International Theatre Festival | International Theatre Festival | 2004 | 2 | |
| Independent Theatre Society, The | The Independent Theatre Society | 1891 – 1997 | 14 | |
| International Ibsen Conference, The | The International Ibsen Conference | 2006 | 1 | |
| Ibsen- og Hamsun-dagene 2008 | Ibsen- og Hamsun-dagene 2008 | 2008 | 1 | |
| Internationale Maifestspiele | Internationale Maifestspiele | 1954 – 2003 | 3 | |
| Infamous Commonwealth Theatre | Infamous Commonwealth Theatre | 2011 | 1 | |
| Ibsen og Hamsun for ungdom 2007 | Ibsen og Hamsun for ungdom 2007 | 2007 | 1 | |
| Ireland Drama Festival | Ireland Drama Festival | | | |
| Il Mecenate APS | Il Mecenate APS | 2014 | 2 | |
| Illini Theatre Guild Laboratory Theatre, The | The Illini Theatre Guild Laboratory Theatre | 1947 – 1949 | 4 | |
| Ida Aalberg-Tournéen | Ida Aalberg-Tournéen | 1904 | 13 | |
| Ibsenkvintetten | Ibsenkvintetten | 2006 | 1 | |
| Ibsenjubileet (Ibsen Anniversary) | Ibsenjubileet (Ibsen Anniversary) | 1928 | 1 | |
| Ibsen Society, The | The Ibsen Society | 1930 | 2 | |
| Ibsen- og Hamsun-dagene 2005 | Ibsen- og Hamsun-dagene 2005 | 2005 | 2 | |
| Ibsen- og Hamsun-dagene 2012 | Ibsen- og Hamsun-dagene 2012 | 2012 | 1 | |
| Ibsen Performance Group | Ibsen Performance Group | 1998 – 2002 | 9 | |
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