| 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 | -- | -- | | | |
| Oppdal Kulturhus | Oppdal Kulturhus | Norway, Oppdal, Inge Krokanns veg 2 | 2009-11-12 | 2015-10-08 | 2009 - 2017 | 5 | |
| Opernhaus | Opernhaus | Germany, Wuppertal, Kurt-Drees-Straße 4 | 2011-06-26 | 2011-12-01 | 2011 | 2 | |
| Orpheum | Orpheum | United States, El Paso | 1908-06-18 | 1908-06-18 | 1908 | 1 | |
| Old Red Lion Theatre | Old Red Lion Theatre | England, London, 418 St John Street | 2000-10-17 | 2000-11-11 | 2000 | 1 | |
| Osnabrücker Hof | Osnabrücker Hof | Germany, Osnabrück, Kollegienwall 14 | 1896-05-13 | -- | 1896 | 1 | |
| Opera House | Opera House | United States, New Castle | 1904-04-29 | 1908-04-11 | 1904 - 1908 | 2 | |
| Officina Giovani - Cantieri Culturali Ex Macelli | Officina Giovani - Cantieri Culturali Ex Macelli | Italy, Prato, Piazza Macelli, 4 | 2007-04-21 | -- | 2007 | 1 | |
| Olivenza | Olivenza | Spain, Olivenza | -- | -- | | | |
| Origosenteret | Origosenteret | Norway, Svinndal, Tyritoppen 19 | 2012-11-26 | -- | 2012 | 2 | |
| Oslo Nye Trikkestallen | Oslo Nye Trikkestallen | Norway, Oslo, Torshovgata 33 | 2011-07-01 | 2011-07-03 | 2011 | 1 | |
| Odin Teatret | Odin Teatret | Denmark, Holstebro, Særkærparken 144 | 2011-- | -- | 2011 - 2016 | 4 | |
| Odd Duck Studio | Odd Duck Studio | United States, Seattle, 1214 10th Avenue | 2008-11-26 | 2008-12-20 | 2008 | 1 | |
| OC De Neerbeek | OC De Neerbeek (Ontmoetingscentrum De Neerbeek) | Belgium, Bissegem, Vlaswaagplein 1 | 2002-01-10 | 2002-01-10 | 2002 - 2007 | 2 | |
| Oradea | Oradea | Romania, Oradea | 1890-08-02 | 1936-08-25 | 1890 - 2012 | 13 | |
| Országos Kamaraszínház | Országos Kamaraszínház | Hungary, Mezőtúr | 1925-09-23 | -- | 1925 - 1927 | 2 | |
| Opernhaus | Opernhaus | Germany, Frankfurt, Opernplatz 1 | 1892-12-10 | -- | 1892 - 1940 | 2 | |
| Odéon-Théâtre de l'Europe | Odéon-Théâtre de l'Europe | France, Paris, 67 Rue Monsieur le Prince | 1993-03-12 | 2005-04-16 | 1993 - 2005 | 4 | |
| Oslo dagene, Akershus Festning | Oslo dagene, Akershus Festning | Norway, Oslo | 1983-08-29 | 1983-09-03 | 1983 | 1 | |
| Ostseebad Göhren | Ostseebad Göhren | Germany, Göhren | 2010-05-04 | -- | 2010 | 1 | |
| OC Vondel (Ontmoetingscentrum Meulebeke) | OC Vondel (Ontmoetingscentrum Meulebeke) | Belgium, Meulebeke, Karel van Manderstraat 26 | 2002-02-28 | 2002-02-28 | 2002 | 1 | |
| Orchard Theatre, the | The Orchard Theatre | England, Dartford, Home Gardens | 1996-03-12 | 1996-03-16 | 1996 | 1 | |
| Ouagadougou, Carrefour Internationale de Théâtre de Ouagadougou | Carrefour Internationale de Théâtre de Ouagadougou | Burkina Faso, Bilbalogho, Ouagadougou, Burkina Faso | 2002-07-13 | -- | 2002 | 1 | |
| Opernhaus Unter den Linden | Opernhaus Unter den Linden | Germany, Berlin | 1905-09-20 | -- | 1905 | 1 | |
| Ovalhouse | Ovalhouse | United Kingdom, London, 52-54 Kennington Oval | 2018-05-17 | 2018-05-19 | 2018 | 1 | |
| Opernhaus Hannover | Opernhaus Hannover | Germany, Hannover, Opernplatz 1 | 1928-03-06 | 1956-12-05 | 1928 - 1956 | 2 | |
| Odense Teater | Odense Teater | Denmark, Odense, Jernbanegade 21 | 1928-04-30 | 2018-10-13 | 1928 - 2018 | 16 | |
| Opera House | Opera House | England, Coventry, 4 Hales Street | 1911-09-11 | 1911-09-14 | 1911 | 1 | |
| Oerlenbach | Oerlenbach | Germany, Oerlenbach | 2009-12-19 | -- | 2009 | 1 | |
| Odeon de Spiegel | Odeon de Spiegel | Netherlands, Zwolle, Blijmarkt 25 | 2000-04-28 | -- | 2000 - 2008 | 2 | |
| Old globe theatre, the | The Old Globe Theatre | United States, San Diego, 1363 Old Globe Way | 1995-04-30 | 1995-06-18 | 1995 | 1 | |
| Olofström | Olofström | Sweden, Olofström | 1992-11-12 | -- | 1992 | 1 | |
| Orleneff’s Russian Lyceum | Orleneff’s Russian Lyceum | United States, New York, East Third Street | 1906-01-03 | -- | 1906 | 1 | |
| Oakland University | Oakland University | United States, Rochester, 2200 North Squirrel Road | 1972-03-02 | 1972-03-26 | 1972 | 1 | |
| Oscar Theatre | Oscar Theatre | Ireland, Dublin | 1980-04-07 | 1980-04-19 | 1980 | 1 | |
| Old Courthouse | Old Courthouse | Northern Ireland, Antrim, Market Square | 2011-05-26 | -- | 2011 | 1 | |
| Odyssey Theatre | Odyssey Theatre | United States, Los Angeles, 2055 S Sepulveda Blvd | 2008-05-02 | 2008-05-25 | 2008 | 1 | |
| Orăștie | Orăștie | Romania, Orăștie | 1911-02-16 | -- | 1911 | 1 | |
| Oslo Nye Dukketeater | Oslo Nye Dukketeater | Norway, Oslo, Rosenkrantz' gate 10 | 1994-08-23 | -- | 1994 | 1 | |
| OBOS-gården Wesselsgate 15 | OBOS-gården Wesselsgate 15 | Norway, Oslo, Museumsveien 10 | 2006-05-20 | 2008-06-13 | 2006 - 2008 | 2 | |
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Venues
