| Olich, Michael | Michael Olich | Costume Designer | 1992 | 1 | |
| Ozoliņa, Lilita | Lilita Ozoliņa | Actor | 1992 | 1 | |
| Obermann, Frank | Frank Obermann | Actor | 1991 | 1 | |
| Otto, Annie | Annie Otto | Actor | 1992 | 1 | |
| O´Regan, Mark | Mark O´Regan | Actor | 1988 | 5 | |
| Ornest, Jiří | Jiří Ornest | Actor | 1988 - 2012 | 2 | |
| Opitz, Gerd | Gerd Opitz | Actor | 1988 | 1 | |
| Op gen Orth, Helga | Helga Op gen Orth | Actor, Adaptation, Director | 1992 - 1996 | 4 | |
| Oimori, Reiko | Reiko Oimori | Actor | 1992 | 1 | |
| Olmo, Francisco | Francisco Olmo | Actor | 1982 | 3 | |
| Ouwehand, Roos | Roos Ouwehand | Actor | 1992 | 1 | |
| Offermans, Sylvia | Sylvia Offermans | Actor | 1992 | 1 | |
| Oeser, Wolf | Wolf Oeser | Actor | 1989 - 1994 | 6 | |
| O'Mahoney, Robert | Robert O'Mahoney | Actor, Author | 1982 - 1991 | 10 | |
| O'Neill, Molly | Molly O'Neill | Actor | 1993 | 1 | |
| O'Hea, Brendan | Brendan O'Hea | Actor | 1993 - 1999 | 6 | |
| Orenstein, Joan | Joan Orenstein | Actor | 1981 - 1991 | 3 | |
| Ogier, Bulle | Bulle Ogier | Actor | 1993 | 4 | |
| Oswald, David | David Oswald | Director | 1993 | 1 | |
| Oswald, Birgit | Birgit Oswald | Actor | 1993 | 1 | |
| O'Brien, Tony | Tony O'Brien | Actor | 1993 | 1 | |
| Obst, Dietmar | Dietmar Obst | Actor | 1993 - 1999 | 2 | |
| Okazaki, Shinobu | Shinobu Okazaki | Designer | 1991 | 1 | |
| Ohsawa, Kaoru | Kaoru Ohsawa | Lighting Designer | 1991 | 1 | |
| Obrecht, Urs | Urs Obrecht | Actor | 1991 | 1 | |
| Overloop, Veerle van | Veerle van Overloop | Actor | 1993 | 1 | |
| Ollinger, Hans | Hans Ollinger | Actor | 1993 | 1 | |
| Ochlast, Jens | Jens Ochlast | Actor | 1993 - 2015 | 3 | |
| Oberholz, Dieter | Dieter Oberholz | Actor | 1993 - 2004 | 3 | |
| Ottosson, Annelie | Annelie Ottosson | Actor | 1993 | 2 | |
| Oskam, Floor | Floor Oskam | Designer | 1991 - 1992 | 14 | |
| Overbeeke, Adri | Adri Overbeeke | Actor | 1991 - 1992 | 84 | |
| Ottlik, Ádám | Ádám Ottlik | Actor | 1996 - 2008 | 2 | |
| Orthmann, Ruth | Ruth Orthmann | Translator | 1994 | 1 | |
| Ott, Friederike | Friederike Ott | Actor | 2014 - 2016 | 12 | |
| Oikonomidou, Miranta | Miranta Oikonomidou | Actor | 1965 - 1994 | 4 | |
| Oliver, Stephen | Stephen Oliver | Composer | 1977 - 1983 | 9 | |
| Ortmayr, Heinrich | Heinrich Ortmayr | Actor | 1982 | 1 | |
| Okhlupin, Igor | Igor Okhlupin (Игорь Охлупин) | Actor | 2013 | 1 | |
| Oberle, Carl-Friedrich | Carl-Friedrich Oberle | Costume Designer, Designer | 1994 | 2 | |
| Oliveira, Vidal de | Vidal de Oliveira | Translator | 1949 - 1994 | 6 | |
| Olszewska, Izabella | Izabella Olszewska | Actor | 1994 | 1 | |
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