| 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 | |
| Ogletree, Kathrine | Kathrine Ogletree | Costume Designer | 2003 | 1 | |
| Olivar, César | César Olivar | Costume Designer | 2004 | 1 | 1 |
| Osswald, Leni | Leni Osswald | Costume Designer | 1955 - 1962 | 2 | |
| Ouyoung, Juliet | Juliet Ouyoung | Costume Designer | 1993 | 1 | |
| O'Clery, Joan | Joan O'Clery | Costume Designer | 2000 - 2013 | 6 | 1 |
| Olsen, Lillian | Lillian Olsen | Costume Designer | 2000 | 7 | |
| Opstad, Cathrine Gåre | Cathrine Gåre Opstad | Costume Designer | 2005 - 2008 | 90 | |
| Owen, Paul | Paul Owen | Costume Designer | 1972 | 1 | |
| O’Keefe, Brian | Brian O’Keefe | Costume Designer | 2009 | 1 | |
| Obuchová, L'ubica | L'ubica Obuchová | Costume Designer | 1985 | 1 | 1 |
| Obermüller, Ulrike | Ulrike Obermüller | Costume Designer | 1991 - 2016 | 2 | |
| Olich, Michael | Michael Olich | Costume Designer | 1992 | 1 | |
| O’Brien, Peter | Peter O’Brien | Costume Designer | 2015 | 1 | |
| Ogata, Kikuko | Kikuko Ogata | Costume Designer | 1968 - 2010 | 2 | |
| Oltványi, Klára | Klára Oltványi | Costume Designer | 2005 | 1 | |
| Opeka, Janel | Janel Opeka | Costume Designer | 2003 | 1 | |
| Oppenberg, Marette | Marette Oppenberg | Costume Designer | 2003 | 2 | 1 |
| Oliver, Anna | Anna Oliver | Costume Designer | 1999 - 2010 | 3 | |
| Olsen Rosing, Anna Nuka | Anna Nuka Olsen Rosing | Costume Designer | 2005 | 1 | |
| Olesen, Ninna | Ninna Olesen | Costume Designer | 2008 | 1 | |
| Orlova, Elena, Ju. | Elena Ju. Orlova | Costume Designer | 2008 - 2011 | 2 | |
| Osborne, Dana | Dana Osborne | Costume Designer | 2011 | 1 | |
| Olsen, Oliver | Oliver Olsen | Costume Designer | 1959 | 2 | |
| Orozco, Hiram Alexander | Hiram Alexander Orozco | Costume Designer | 2016 | 1 | |
| Owen-Maclean, - | - Owen-Maclean | Costume Designer | 1950 | 1 | |
| Otero, Cachi | Cachi Otero | Costume Designer | 1971 | 3 | |
| Oditz, Carol | Carol Oditz | Costume Designer | 1981 | 1 | |
| O'Gara, Penn | Penn O'Gara | Costume Designer | 2019 | 1 | |
| Oliver, Sarah, M. | Sarah M. Oliver | Costume Designer | 2019 | 1 | |
| Obendorf, Lujo | Lujo Obendorf | Costume Designer | 1952 | 1 | |
| 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 | |
| Oroșanu, Cristian | Cristian Oroșanu | Conductor | 2012 | 1 | |
| Olariu, Stelian | Stelian Olariu | Conductor | 2007 | 1 | |
| Ovodok, Vladimir | Vladimir Ovodok | Conductor | 2020 | 1 | |
| Oikonomou, Thodoris | Thodoris Oikonomou | Composer, Musician | 2007 - 2020 | 2 | |
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