| O'Shaughnessy, Fiona | Fiona O'Shaughnessy | Actor | 2008 | 2 | |
| Orlova, Elena, Ju. | Elena Ju. Orlova | Costume Designer | 2008 - 2011 | 2 | |
| Omdal, Adrian | Adrian Omdal | Actor | 2016 - 2017 | 2 | |
| Obi, Christopher | Christopher Obi | Actor | 2008 | 2 | |
| O'Dowd, Spencer | Spencer O'Dowd | Actor | 2008 | 2 | |
| Orlac, Stephan | Stephan Orlac | Actor | 1966 | 2 | |
| Ochsenbauer, Georg | Georg Ochsenbauer | Lighting Designer, Sound Designer | 2016 | 2 | |
| Oja, Andres | Andres Oja | Actor | 2001 - 2010 | 2 | |
| Oseng, Ellen | Ellen Oseng | Costume Designer, Designer | 2009 | 2 | |
| Ohinmaa, Hertta-Maija | Hertta-Maija Ohinmaa | Actor | 2009 | 2 | |
| O'Brien, Keith | Keith O'Brien | Musical Director | 2016 - 2019 | 2 | |
| Osburn, Nathan | Nathan Osburn | Actor | 2011 | 2 | |
| Olivo, Oscar | Oscar Olivo | Actor | 2013 - 2022 | 2 | |
| Oechel, Hagen | Hagen Oechel | Actor | 2012 - 2015 | 2 | 2 |
| Ostapenko, Alexandra | Alexandra Ostapenko | Actor | 2015 - 2022 | 2 | |
| Oehl, Fabian | Fabian Oehl | Actor | 2012 | 2 | |
| O'Reilly, Vincent, A. | Vincent A. O'Reilly | Adaptation, Director | 2012 | 2 | 1 |
| Olsen, Clifford, R. | Clifford R. Olsen | Actor, Director | 1963 | 2 | 1 |
| Orea, Mario | Mario Orea | Actor | 1961 - 1963 | 2 | |
| O'Connell, Moya | Moya O'Connell | Actor, Director | 2012 - 2024 | 2 | 1 |
| O'Connor, Boardman | Boardman O'Connor | Designer, Lighting Designer | 1961 | 2 | |
| O'Brien, Adale | Adale O'Brien | Actor | 1961 - 1962 | 2 | |
| O'Keefe, Tim | Tim O'Keefe | Actor | 2012 | 2 | |
| O'Connell, Dan | Dan O'Connell | Actor, Director | 1943 - 1961 | 2 | |
| O’Shaughnessy, Hilary | Hilary O’Shaughnessy | Actor | 2011 | 2 | |
| O’Connell, Will | Will O’Connell | Actor | 2011 | 2 | |
| Orlenco, Alexej | Alexej Orlenco | Actor | 2011 | 2 | |
| Olćan, Olga | Olga Olćan | Actor | 2011 | 2 | |
| Olsen, Oliver | Oliver Olsen | Costume Designer | 1959 | 2 | |
| Oliver, Norman | Norman Oliver | Actor | 1959 | 2 | |
| Olsen, Jens-Anker | Jens-Anker Olsen | Designer | 1954 - 1956 | 2 | |
| Olinescu, Boris | Boris Olinescu | Actor, Assistant Director | 1959 | 2 | |
| Ovaska, Sulo | Sulo Ovaska | Actor, Designer | 1956 | 2 | |
| Ohki, Yasushi | Yasushi Ohki | Director | 1955 - 1956 | 2 | |
| Olin, Kerstin | Kerstin Olin | Actor | 1953 | 2 | |
| Oy, Necmi | Necmi Oy | Actor | 1956 | 2 | |
| Opsahl, Svein, Eirik | Svein Eirik Opsahl | Actor | 1956 | 2 | |
| Odegard, Mary Sue | Mary Sue Odegard | Actor | 1963 | 2 | |
| Orgulas, Jaanus | Jaanus Orgulas | Actor | 1962 - 1989 | 2 | |
| Ollila, Yrjö | Yrjö Ollila | Costume Designer, Designer | 1930 | 2 | |
| Oppenheimer, Albert, M. | Albert M. Oppenheimer | Actor | 1931 | 2 | |
| Ostrižnaja, O. | O. Ostrižnaja | Lighting Designer | 1999 - 2000 | 2 | |
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