| O'Connor, Paul, Vincent | Paul Vincent O'Connor | Actor | 1990 | 3 | |
| Ottmann, Anna | Anna Ottmann | Actor | 1992 - 2000 | 3 | 1 |
| Olmo, Francisco | Francisco Olmo | Actor | 1982 | 3 | |
| Orenstein, Joan | Joan Orenstein | Actor | 1981 - 1991 | 3 | |
| Ochlast, Jens | Jens Ochlast | Actor | 1993 - 2015 | 3 | |
| Oberholz, Dieter | Dieter Oberholz | Actor | 1993 - 2004 | 3 | |
| Oliver, Tim | Tim Oliver | Sound Designer | 1994 - 1995 | 3 | |
| Ohshima, Nobuhisa | Nobuhisa Ohshima | Actor, Adaptation, Director | 1994 | 3 | |
| Oristânio, Giuseppe | Giuseppe Oristânio | Actor | 1997 - 1998 | 3 | |
| Ombuen, Gianfranco | Gianfranco Ombuen | Actor | 1967 - 1969 | 3 | |
| Otto, Franz | Franz Otto | Actor | 1917 - 1924 | 3 | |
| Olmsted, Richard | Richard Olmsted | Designer, Lighting Designer | 2002 - 2003 | 3 | |
| Oliver, Anna | Anna Oliver | Costume Designer | 1999 - 2010 | 3 | |
| Otčenášek, Štěpán | Štěpán Otčenášek | Dramaturg | 2013 | 3 | |
| Okpokwasili, Okwui | Okwui Okpokwasili | Actor | 2003 - 2010 | 3 | 1 |
| Owe, Bård | Bård Owe | Actor | 2004 - 2005 | 3 | 1 |
| Oscarsson, Ulrika | Ulrika Oscarsson | Actor, Musician | 2001 | 3 | |
| Oniga, Laurian | Laurian Oniga | Designer | 1985 | 3 | |
| Oltean, Silviu | Silviu Oltean | Actor | 2009 | 3 | |
| Ortiz, Alain | Alain Ortiz | Designer | 2006 | 3 | |
| Oliver, Barbara | Barbara Oliver | Actor, Director | 2006 - 2010 | 3 | 1 |
| Oura, Mizuki | Mizuki Oura | Actor | 2006 | 3 | |
| Olivi, Laura | Laura Olivi | Dramaturg | 2006 - 2007 | 3 | |
| Orth, Franz | Franz Orth | Actor | 2007 | 3 | |
| Ouellette, Jean-Sébastien | Jean-Sébastien Ouellette | Actor | 2009 - 2022 | 3 | 1 |
| O'Neill, Michelle | Michelle O'Neill | Actor | 2008 | 3 | |
| Olt, Edgar | Edgar Olt | Actor | 1955 | 3 | |
| Ono, Y. | Y. Ono | Dramaturg | 2008 - 2009 | 3 | |
| Ott, Karl | Karl Ott | Actor | 1880 - 1893 | 3 | |
| Ono, Hacchaku | Hacchaku Ono | Dramaturg | 2009 | 3 | |
| Oblokar, Samo | Samo Oblokar | Lighting Designer | 2010 - 2012 | 3 | |
| Obst, Angela | Angela Obst | Dramaturg | 2012 - 2021 | 3 | |
| O'Mahony, Paul | Paul O'Mahony | Designer | 2013 - 2017 | 3 | |
| Ohlsson, Fredrik | Fredrik Ohlsson | Actor | 1957 | 3 | |
| Oosterwijk, Nora | Nora Oosterwijk | Actor | 1956 - 1957 | 3 | |
| Orendy, C. | C. Orendy | Actor | 1920 - 1928 | 3 | |
| Okkola, Helena | Helena Okkola | Actor | 1998 | 3 | |
| O’Hearn, Robert | Robert O’Hearn | Actor, Designer | 1949 - 1950 | 3 | |
| Oates, Cicely | Cicely Oates | Actor | 1930 | 3 | |
| Orbeck, Anders | Anders Orbeck | Translator | 1936 - 2018 | 3 | 1 |
| Otero, Cachi | Cachi Otero | Costume Designer | 1971 | 3 | |
| Olson, Niclas | Niclas Olson | Actor, Adaptation, Director | 2017 | 3 | |
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