| Oleinick, Tracy | Tracy Oleinick | Costume Designer | | 1 | |
| O’Clery, Joan | Joan O’Clery | Costume Designer | 2023 | 1 | |
| Onnis, Valeria | Valeria Onnis | Costume Designer | 2012 | 2 | |
| Oramusc, Anna | Anna Oramusc | Costume Designer | 2022 | 1 | |
| Oelkers, Uwe | Uwe Oelkers | Costume Designer, Designer | 1985 - 2010 | 7 | |
| Ohland, Hans | Hans Ohland | Costume Designer, Designer | 1963 - 1981 | 4 | |
| Ojamaa, Pekka | Pekka Ojamaa | Costume Designer, Designer | 1990 - 2001 | 9 | |
| O'Brien, Timothy | Timothy O'Brien | Costume Designer, Designer | 1964 - 1996 | 12 | |
| Olsen, Thale Kvam | Thale Kvam Olsen | Costume Designer, Designer | 2013 | 4 | |
| Oechslin, Ary | Ary Oechslin | Costume Designer, Designer | 1952 - 1978 | 11 | 1 |
| Oskam, Peter | Peter Oskam | Costume Designer, Designer | 1985 | 2 | |
| Oberle, Carl-Friedrich | Carl-Friedrich Oberle | Costume Designer, Designer | 1994 | 2 | |
| O'Malley, Geraldine | Geraldine O'Malley | Costume Designer, Designer | 1989 - 1990 | 4 | |
| Olsson, Marie | Marie Olsson | Costume Designer, Designer | 2014 | 2 | |
| Oxlade, Jonathon | Jonathon Oxlade | Costume Designer, Designer | 2007 | 2 | 1 |
| Otto, Frank-Tilmann | Frank-Tilmann Otto | Costume Designer, Designer | 2008 | 4 | |
| Oseng, Ellen | Ellen Oseng | Costume Designer, Designer | 2009 | 2 | |
| Ollila, Yrjö | Yrjö Ollila | Costume Designer, Designer | 1930 | 2 | |
| Orfanos, Lampros | Lampros Orfanos | Costume Designer, Designer | 1943 | 2 | |
| Otto, Teo | Teo Otto | Costume Designer, Designer, Director | 1934 - 1959 | 14 | |
| Ovanessian, Arby | Arby Ovanessian | Costume Designer, Designer, Director | 1970 | 3 | 1 |
| Oenslager, Donald | Donald Oenslager | Costume Designer, Designer, Lighting Designer | 1934 - 1951 | 19 | 1 |
| Opsvig, Virginia | Virginia Opsvig | Costume Designer, Mask Maker | 1931 - 1936 | 4 | |
| Olenina, E. | E. Olenina | Dancer | 1999 - 2000 | 2 | |
| Olstad, Jon Ole | Jon Ole Olstad | Dancer | 2011 | 1 | |
| Olsen, Gudrun | Gudrun Olsen | Dancer | 1928 | 1 | |
| Okafor, Stella C | Stella C Okafor | Dancer | 2002 | 1 | |
| Okafor, Stella O | Stella O Okafor | Dancer | 2002 | 1 | |
| Olsen, Mikkel, Are | Mikkel Are Olsen | Dancer | 2006 | 1 | |
| O'Donnell, Carolyn | Carolyn O'Donnell | Dancer | 1956 | 1 | |
| Oulianine, Nina | Nina Oulianine | Dancer | 1937 | 1 | |
| Olsen, Lisbeth-Anita, Grimsø | Lisbeth-Anita Grimsø Olsen | Dancer | 2017 | 1 | |
| O'Reilly, Kiera Lee | Kiera Lee O'Reilly | Dancer | 2024 | 1 | |
| Okun, Alexander | Alexander Okun | Designer | 1992 - 2003 | 3 | 1 |
| Otto, Wilfried | Wilfried Otto | Designer | 1958 | 1 | |
| Owen, Hugh | Hugh Owen | Designer | 1927 | 1 | |
| Orling, O. | O. Orling | Designer | 1895 | 2 | |
| Orling, E. | E. Orling | Designer | 1895 - 1896 | 6 | |
| og Bauer, Breitner | Breitner og Bauer | Designer | 1897 | 1 | |
| Obstfelder, Helmut | Helmut Obstfelder | Designer | 1949 | 1 | |
| Okada, Saburonosuke | Saburonosuke Okada | Designer | 1909 | 1 | |
| Opperud, Knut | Knut Opperud | Designer | 1994 | 1 | |
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