| Odessa | Одеса (Odessa) | Ukraine, Odessa | -- | -- | | | |
| Overture Center for the Arts, The Playhouse | Overture Center for the Arts, The Playhouse | United States, Madison, 201 State St | 2010-03-18 | 2010-03-28 | 2010 | 1 | |
| Oscar Theatre | Oscar Theatre | Ireland, Dublin | 1980-04-07 | 1980-04-19 | 1980 | 1 | |
| Otto-Klenert-Schule | Otto-Klenert-Schule | Germany, Bad Friedrichshall, Rathausplatz 7 | 2006-02-18 | -- | 2006 | 1 | |
| Orpheum | Orpheum | Germany, Munich | 1893-03-08 | -- | 1893–1895 | 3 | |
| Olomouc | Olomouc | Czech Republic, Olomouc | 2007-05-17 | -- | 2007 | 1 | |
| Oslo Rådhus | Oslo Rådhus | Norway, Oslo, Rådhusplassen 1 | 2009-03-28 | -- | 2009 | 1 | |
| Örebro | Örebro (Oerebro) | Sweden, Örebro | 1936-09-27 | -- | 1936–1970 | 3 | |
| Opern- und Schauspielhaus Hannover | Opern- und Schauspielhaus Hannover | Germany, Hannover | 1920-06-21 | -- | 1920–1924 | 2 | |
| Oblastnoi dramatičeskij teatr | Oblastnoi dramatičeskij teatr | Russia, Veliky Novgorod | 1948-09- | -- | 1948 | 1 | |
| Oulu | Oulu | Finland, Oulu | -- | -- | | | |
| Ogra | Ogra | Romania, Ogra | -- | -- | | | |
| Oravița | Oravița | Romania, Oravița | 1884-12-08 | 1884-12-23 | 1884–1913 | 3 | |
| Octagon, The | The Octagon | United States, Montgomery, 1 Festival Drive | 1997-03-04 | 2002-04-14 | 1997–2002 | 2 | |
| Odeon | Odeon | Argentina, Buenos Aires | 1904-06-24 | 1904-06-26 | 1904 | 1 | |
| Olavshallen | Olavshallen | Norway, Trondheim, Kjøpmannsgata 44 | 1997-05-15 | 2008-02-29 | 1997–2008 | 5 | |
| Onassis Cultural Centre, Upper Stage | Onassis Cultural Centre, Upper Stage | Greece, Athens, 107-109 Syngrou Avenue | 2014-12-22 | 2015-01-04 | 2014–2015 | 2 | |
| Oslo Nye Teater (Centralteatret) | Oslo Nye Teater (Centralteatret) | Norway, Oslo, Akersgata 38 | 1972-09-28 | 2017-06-17 | 1972–2017 | 10 | |
| Opera House | Opera House | United States, Bemidji | 1904-09-20 | 1904-09-20 | 1904 | 1 | |
| Open Scene Orlando (Instagram) | Open Scene Orlando (Instagram) | United States, Orlando | 2020-05-07 | 2020-06-10 | 2020 | 1 | |
| Oslo Public Library | Oslo Public Library | Norway, Oslo, Arne Garborgs plass 4 | 1988-06-30 | -- | 1988 | 1 | |
| Ogólnopolski Festiwal Sztuki Reżyserskiej INTERPRETACJE | Ogólnopolski Festiwal Sztuki Reżyserskiej INTERPRETACJE | Poland, Katowice, Sejmu Śląskiego 2 | 2016-11-12 | 2016-11-12 | 2016 | 1 | |
| Old American Can Factory, The | The Old American Can Factory | United States, Brooklyn, 232 3rd Street | 2003-03-06 | 2003-06-07 | 2003 | 2 | |
| Odda | Odda | Norway, Odda | 1951-04-25 | 1958-03-02 | 1951–1982 | 6 | |
| Odensbacken | Odensbacken | Sweden | 2002-09-12 | -- | 2002 | 1 | |
| Origosenteret | Origosenteret | Norway, Svinndal, Tyritoppen 19 | 2012-11-26 | -- | 2012 | 2 | |
| Opera House | Opera House | United States, Santa Cruz | 1905-07-28 | 1905-07-28 | 1905 | 1 | |
| Orosháza | Orosháza | Hungary, Orosháza | 1890-05-12 | -- | 1890–1926 | 6 | |
| Öteki Tiyatro | Öteki Tiyatro | Turkey, Maltepe/ANKARA, Gazi Mustafa Kemal Bulvarı No:114-C | 2007-06-23 | -- | 2007 | 1 | |
| Orăștie | Orăștie | Romania, Orăștie | 1911-02-16 | -- | 1911 | 1 | |
| Obergrafschaft, Theater der | Theater der Obergrafschaft | Germany, Schüttorf, Hermann-Schlikker-Str. 1-3 | 2015-10-03 | -- | 2015 | 1 | |
| Östersund | Östersund | Sweden, Östersund | 1879-- | -- | 1879 | 1 | |
| Omskiy Gosudarstvennyy Dramaticheskiy Pyatyy Teatr | Omskiy Gosudarstvennyy Dramaticheskiy Pyatyy Teatr | Russia, Omsk, ul. Krasnyy Put' 153 | 2005-10-01 | -- | 2005 | 1 | |
| Opera House | Opera House | United States, Hopkinsville | 1904-11-23 | 1904-11-23 | 1904 | 1 | |
| Old Tote Theatre, The | The Old Tote Theatre | Australia, Kensington, High Street | 1967-09-23 | 1971-08-03 | 1967–1971 | 2 | |
| Oberammergau, Passionstheater | Passionstheater Oberammergau | Germany, Oberammergau, Othmar-Weis-Str. | 2016-07-01 | 2016-07-23 | 2016 | 1 | |
| Odd Duck Studio | Odd Duck Studio | United States, Seattle, 1214 10th Avenue | 2008-11-26 | 2008-12-20 | 2008 | 1 | |
| Ontmoetingscentrum Aalbeke | Ontmoetingscentrum Aalbeke | Belgium, Aalbeke, Aalbekeplaats | 2001-03-12 | 2001-03-12 | 2001 | 1 | |
| Olde Towne Hall Theatre | Olde Towne Hall Theatre | United States, North Ridgeville, 36119 Center Ridge Road | 2018-05-18 | 2018-05-19 | 2018 | 1 | |
| Ostróg | Ostróg | Poland, Ostróg | -- | -- | | | |
| Old Rep at Birmingham Repertory Theatre | The Old Rep at Birmingham Repertory Theatre | England, Birmingham | 2013-03-14 | 2013-03-28 | 2013 | 1 | |
| ORF Radio (Austria) | ORF Radio (Austria) | Austria | 1991-04-18 | -- | 1991 | 1 | |
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