| Ocna Sibiului | Ocna Sibiului | Romania, Ocna Sibiului | -- | -- | | | |
| Oberschlesisches Grenzlandtheater Ratibor | Oberschlesisches Grenzlandtheater Ratibor | Poland, Ratibor / Racibórz | 1937-02-19 | -- | 1937 | 1 | |
| Opština Bečej | Opština Bečej | Serbia, Opština Bečej | 1903-03-11 | -- | 1903 | 1 | |
| Oblastnoj teatr dramy | Oblastnoj teatr dramy | Russia, Čeljabinsk | 1980-09- | -- | 1980 | 1 | |
| Operahuset Nordfjord | Operahuset Nordfjord | Norway, Nordfjord, Sophus Lie-vegen 3 | 2009-11-09 | -- | 2009 - 2017 | 6 | |
| Oslo | Oslo | Norway, Oslo | 1928-02-28 | 2008-10-02 | 1928 - 2014 | 9 | |
| Ophelia Theater | Ophelia Theater | United States, Astoria, 21-12 30th Road | 2016-10-28 | 2016-11-13 | 2016 | 1 | |
| Odessa | Одеса (Odessa) | Ukraine, Odessa | -- | -- | | | |
| Orpheum Theatre | Orpheum Theatre | United States, Salt Lake City | 1908-06-13 | 1908-06-13 | 1908 | 1 | |
| Oravice | Oravice | Slovak Republic, Oravice | -- | -- | | | |
| Odense Theater | Odense Theater | Denmark, Odense, Sortebrødre Torv | 1876-04-20 | 1899-10-20 | 1876 - 1901 | 9 | |
| Oxfordshire | Oxfordshire | England | 2020-05-08 | -- | 2020 | 1 | |
| Orkdal Kulturhus | Orkdal Kulturhus | Norway, Orkanger, Orkanger | 2012-11-11 | 2015-10-09 | 2012 - 2015 | 4 | |
| Ohio State University | Ohio State University | United States, Columbus, 1739 North High Street | 1981-02-27 | 2001-03-04 | 1981 - 2001 | 2 | |
| Opernhaus Graz | Opernhaus Graz | Austria, Graz, Opernring | 1912-05-24 | -- | 1912 | 2 | |
| Old Rep at Birmingham Repertory Theatre | The Old Rep at Birmingham Repertory Theatre | England, Birmingham | 2013-03-14 | 2013-03-28 | 2013 | 1 | |
| Opera House | Opera House | United States, McCook | 1905-03-16 | 1905-03-16 | 1905 | 1 | |
| Opéra de Rouen | Opéra de Rouen | France, Rouen, 7 rue du Docteur Rambert | 2003-11-29 | 2003-11-30 | 2003 | 1 | |
| Óbudai Kisfaludy Színház | Óbudai Kisfaludy Színház | Hungary, Budapest | 1900-04-15 | -- | 1900 | 1 | |
| Oulun Kaupunginteatteri | Oulun Kaupunginteatteri | Finland, Oulu, Kaarlenväylä 2 | 1963-- | 1972-04-27 | 1963 - 1985 | 3 | |
| Old Vic, The | The Old Vic | England, London, The Cut | 1922-03-06 | 2016-03-19 | 1922 - 2016 | 11 | |
| Opera Comique Theatre | Opera Comique Theatre | England, London | 1889-07-17 | 1895-03-30 | 1889 - 1895 | 6 | |
| Ottumwa | Ottumwa | United States, Ottumwa | 1903-11-04 | 1903-11-04 | 1903 | 1 | |
| Opernhaus, Städtische Theater Karl-Marx-Stadt | Städtische Theater Karl-Marx-Stadt (Opernhaus) | Germany, Karl-Marx-Stadt (Chemnitz), Theaterplatz | 1956-04-29 | -- | 1956 | 1 | |
| Odensbacken | Odensbacken | Sweden | 2002-09-12 | -- | 2002 | 1 | |
| Oulu | Oulu | Finland, Oulu | -- | -- | | | |
| Oppdal | Oppdal | Norway, Oppdal | -- | -- | | | |
| Opéra-Théâtre i Avignon | Opéra-Théâtre i Avignon | France, Avignon, 1 Rue Racine | 2012-07-18 | 2012-07-25 | 2012 | 1 | |
| Opera House | Opera House | United States, San Juan | 1905-05-06 | 1905-05-06 | 1905 | 1 | |
| Olympia Theatre | Olympia Theatre | Ireland, Dublin, 72 Dame St | 1954-07-05 | -- | 1954 | 1 | |
| Old Fire Station Studio Theatre | Old Fire Station Studio Theatre | England, Oxford, 40 George St | 2003-11-11 | 2018-10-06 | 2003 - 2018 | 2 | |
| Optima Playhouse | Optima Playhouse | Australia, Adelaide, Festival Drive | 1999-07-06 | 1999-07-24 | 1999 | 1 | |
| Oskarshamn | Oskarshamn | Sweden, Oskarshamn | 1991-05-03 | 1991-05-03 | 1991 - 1992 | 2 | |
| Opernhaus Chemnitz | Opernhaus Chemnitz | Germany, Chemnitz, Theaterstraße 2 | 1927-09-27 | -- | 1927 - 1991 | 4 | |
| Onafhankelijk Toneel | Onafhankelijk Toneel | Netherlands, Rotterdam, Sint-Jobsweg 3 | 1998-05-21 | 2009-11-22 | 1998 - 2009 | 4 | |
| Opera House | Opera House | United States, Hopkinsville | 1904-11-23 | 1904-11-23 | 1904 | 1 | |
| Operettenhaus | Operettenhaus | Germany, Düsseldorf, Jahnstraße | 1952-11-01 | -- | 1952 | 1 | |
| Olympic Theatre | Olympic Theatre | United States, St. Louis | 1891-01-11 | 1910-04-03 | 1891 - 1910 | 7 | |
| Opera House | Opera House | United States, Dixon | 1904-11-30 | 1907-12-21 | 1904 - 1907 | 2 | |
| Omskiy Gosudarstvennyy Dramaticheskiy Pyatyy Teatr | Omskiy Gosudarstvennyy Dramaticheskiy Pyatyy Teatr | Russia, Omsk, ul. Krasnyy Put' 153 | 2005-10-01 | -- | 2005 | 1 | |
| Ostrava | Ostrava | Czech Republic, Ostrava | -- | -- | | | |
| Odeon | Odeon | Argentina, Buenos Aires | 1904-06-24 | 1904-06-26 | 1904 | 1 | |
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Venues
