| Otto, Herr | Herr Otto | Actor, Director | 1878 | 2 | |
| Olin, Vilhelm | Vilhelm Olin | Actor, Director | 1886 - 1919 | 4 | 1 |
| Ozoliņš, Pēteris | Pēteris Ozoliņš | Actor, Director | 1889 - 1912 | 5 | |
| Outram, Leonard | Leonard Outram | Actor, Director | 1891 - 1897 | 7 | 1 |
| Odemar, Fritz | Fritz Odemar | Actor, Director | 1893 - 1934 | 5 | |
| Osmarr, Otto | Otto Osmarr | Actor, Director | 1889 - 1919 | 23 | |
| Oikonomou, Thomas | Thomas Oikonomou | Actor, Director | 1902 - 1926 | 121 | |
| Ognjanov, Sava | Sava Ognjanov | Actor, Director | 1905 - 1928 | 8 | |
| Orlenev, Pavel | Pavel Orlenev | Actor, Director | 1903 - 1923 | 14 | 1 |
| Ones, Arvid | Arvid Ones | Actor, Director | 1983 - 2004 | 22 | 1 |
| Osis, Jānis | Jānis Osis | Actor, Director | 1921 - 1943 | 5 | |
| Oden, Christopher | Christopher Oden | Actor, Director | 1984 - 2001 | 6 | 1 |
| Oliver, Barbara | Barbara Oliver | Actor, Director | 2006 - 2010 | 3 | 1 |
| Olsen, Arne, Thomas | Arne Thomas Olsen | Actor, Director | 1955 - 1963 | 19 | 1 |
| Olsen, Clifford, R. | Clifford R. Olsen | Actor, Director | 1963 | 2 | 1 |
| O'Connell, Moya | Moya O'Connell | Actor, Director | 2012 - 2024 | 2 | 1 |
| O'Connell, Dan | Dan O'Connell | Actor, Director | 1943 - 1961 | 2 | |
| Orell, Heinrich | Heinrich Orell | Actor, Director | 1911 | 2 | |
| Otto, Alex | Alex Otto | Actor, Director, Playwright | 1898 - 1934 | 21 | |
| Oscar, Henry | Henry Oscar | Actor, Director, Producer | 1930 - 1947 | 5 | |
| Oswald, Richard | Richard Oswald | Actor, Director, Producer | 1910 - 1919 | 10 | |
| Ohkubo, Ryoichi | Ryoichi Ohkubo | Actor, Director, Translator | 1996 - 2006 | 4 | |
| Oertzen, Dietrich v. | Dietrich v. Oertzen | Actor, Dramaturg, Translator | 1981 | 3 | |
| Overbury, Fran | Fran Overbury | Actor, Musical Director | 2001 | 5 | |
| Olausson, Hilde | Hilde Olausson | Actor, Musician | 1985 - 2015 | 8 | 3 |
| Oscarsson, Ulrika | Ulrika Oscarsson | Actor, Musician | 2001 | 3 | |
| Organ, Alex | Alex Organ | Actor, Sound Designer | 2002 | 2 | |
| Orak, Aydin | Aydin Orak | Actor, Translator | 2010 | 16 | 2 |
| Otrembowa, Julia | Julia Otrembowa | Actor, Translator | 1883 - 1899 | 4 | |
| Oranowski, Bronisław | Bronisław Oranowski | Actor, Translator | 1907 - 1911 | 3 | |
| O'Lochlainn, Gearoid | Gearoid O'Lochlainn | Actor, Translator | 1928 - 2009 | 2 | |
| Ollén, Gunnar | Gunnar Ollén | Adaptation | 1947 - 2005 | 2 | 1 |
| Osztovits, Cecilia | Cecilia Osztovits | Adaptation | 2002 | 1 | 1 |
| Oxenvad, Ann Sofie | Ann Sofie Oxenvad | Adaptation | 2003 | 1 | 1 |
| Oakes, Robert | Robert Oakes | Adaptation | 2009 | 1 | |
| O’Hearn, Nigel | Nigel O’Hearn | Adaptation | 2011 - 2016 | 4 | |
| O'Rowe, Mark | Mark O'Rowe | Adaptation | 2016 | 1 | 1 |
| O'Horn, Nigel | Nigel O'Horn | Adaptation | 2017 | 1 | |
| Otten, Joe | Joe Otten | Adaptation | 2018 | 1 | |
| Ocano, Armando | Armando Ocano | Adaptation | 1975 - 1980 | 5 | |
| Orlikowsky, Wazlaw | Wazlaw Orlikowsky | Adaptation, Choreographer, Director | 1956 - 1964 | 4 | 1 |
| Oikonomopoulou, Pepi | Pepi Oikonomopoulou | Adaptation, Director | 2006 | 2 | |
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