| Ohkata, Hisako | Hisako Ohkata | Actor | 1978 - 1983 | 2 | |
| Okada, Kazuo | Kazuo Okada | Director, Musical Director | 1969 - 1978 | 2 | |
| Osborne, Nina | Nina Osborne | Actor | 1912 | 1 | |
| O'Neill, Norman | Norman O'Neill | Composer | 1913 | 1 | |
| Orchardson, Yvonne Q. | Yvonne Q. Orchardson | Actor | 1913 | 1 | |
| Oudinotis, Alekos | Alekos Oudinotis | Actor | 1975 - 1985 | 5 | |
| O'Connor, Cecile | Cecile O'Connor | Actor | 1973 | 7 | |
| Oschlag, Jakob | Jakob Oschlag | Adaptation, Director | 1977 - 2001 | 8 | |
| Ohnesorge, Helli | Helli Ohnesorge | Actor | 1978 - 1986 | 2 | |
| Ostrowsky, Hartmut | Hartmut Ostrowsky | Director | 1975 | 1 | |
| Orr, Terence | Terence Orr | Sound Designer | 1975 | 1 | |
| Otto, Julius | Julius Otto | Actor | 1880 - 1898 | 6 | |
| Orešković, Želimir | Želimir Orešković | Director | 1975 - 1989 | 3 | |
| Owen, Brett | Brett Owen | Actor | 1979 | 1 | |
| Ognjanović, Aleksandar | Aleksandar Ognjanović | Director | 1955 - 1979 | 4 | |
| Oikonomidou, Rania | Rania Oikonomidou | Actor | 1976 - 2004 | 7 | |
| Ohlschewski, Gerhard | Gerhard Ohlschewski | Actor | 1975 | 2 | |
| Olschok, Herbert | Herbert Olschok | Director | 1988 - 2014 | 5 | |
| Ostrowicz, Kazimierz | Kazimierz Ostrowicz | Actor | 1975 | 1 | |
| Ostrowski, Janusz | Janusz Ostrowski | Actor | 1975 | 2 | |
| Osborn, Sally | Sally Osborn | Actor | 1975 | 1 | |
| Ogăşanu, Virgil | Virgil Ogăşanu | Actor | 1969 - 2006 | 6 | |
| Ogasawara, Yoshitomo | Yoshitomo Ogasawara | Actor | 1976 - 1990 | 4 | |
| Opaker, Eva | Eva Opaker | Actor | 1973 | 1 | |
| Owens, Elizabeth | Elizabeth Owens | Actor | 1971 - 1979 | 2 | |
| Otto, Carsten | Carsten Otto | Actor | 1975 - 1976 | 2 | |
| Oberhof, Johannes | Johannes Oberhof | Actor | 1972 | 2 | |
| Ozolins, Miervaldis | Miervaldis Ozolins | Actor | 1964 - 1975 | 2 | |
| Oglesby, Marshall | Marshall Oglesby | Director | 1973 | 1 | |
| Obuch, Ladislav | Ladislav Obuch | Translator | 1955 - 2021 | 14 | |
| Oertzen, Dietrich v. | Dietrich v. Oertzen | Actor, Dramaturg, Translator | 1981 | 3 | |
| O' Mahony, Tom | Tom O' Mahony | Actor | 1979 | 1 | |
| Otto, Bailey | Bailey Otto | Designer | 2014 | 1 | |
| Occhini, Ilaria | Ilaria Occhini | Actor | 1981 - 2005 | 19 | |
| Orthofer, Monika | Monika Orthofer | Actor | 1981 | 5 | |
| Osborne, Kipp | Kipp Osborne | Actor | 1976 | 1 | |
| Okking, Jens | Jens Okking | Actor | 1979 - 1984 | 4 | |
| Osborne, John | John Osborne | Adaptation, Translator | 1972 - 2011 | 8 | |
| O'Brien, Sylvia | Sylvia O'Brien | Actor | 1981 | 1 | |
| O´Neill, Noel | Noel O´Neill | Actor | 1979 | 1 | |
| Ostermann, Lothar | Lothar Ostermann | Actor | 1960 - 1976 | 6 | |
| Otsus, Velda | Velda Otsus | Actor | 1962 - 1976 | 2 | |
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