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| Ó Riada, Seán (1931 - 1971) Ireland |
| O'Brien, JoyEllen (? - ) U.S.A. |
| O'Connell, Katharine (1971 - ) U.S.A. |
| O'Connell, Kevin (1958 - ) Ireland |
| O'Dwyer, Timothy (1971 - ) Australia |
| O'Leary, Jane (1946 - ) Ireland |
| O'Leary, Martin (1963 - ) Ireland |
| O'Neill, Nicholas (1970 - ) United Kingdom |
| O'Regan, Tarik (1978 - ) United Kingdom |
| Obermaier, Klaus (1955 - ) Austria |
| Obermüller, Karola (1977 - ) Germany |
| Obrovská, Jana (1930 - 1987) Czech Republic |
| Ocampo, Sergio (? - ) Mexico |
| Ocaña, Anthony (1980 - ) Spain |
| Ochoa, Luis (1959 - ) Venezuela |
| Ockert, Matthias (1970 - ) Germany |
| Odriozola, Ricardo (1965 - ) Norway |
| Odstrcil, Karel (1930 - 1997) Czech Republic |
| Oehring, Helmut (1961 - ) Germany |
| Ofenbauer, Christian (1961 - ) Austria |
| Ogawa, Takashi (1960 - ) Japan |
| Ogino, Mutsuhito (1981 - ) Japan |
| Oh, Seung-Ah (1969 - ) Korea |
| Ohana, Maurice (1914 - 1992) France |
| Ólafsson, Kjartan (1958 - ) Iceland |
| Olavide, Gonzalo de (1934 - 2005) Spain |
| Olbrisch, Franz Martin (1952 - ) Germany |
| Olczak, Krzysztof (1956 - ) Poland |
| Oldrini, Norberto (1968 - ) Italy |
| Olivari, Arcángel Castillo (1959 - ) Venezuela |
| Olive, Vivienne (1950 - ) Australia |
| Oliveira, Fernando Correia de (1921 - 2004) Portugal |
| Oliveira, Jamary (1944 - ) Brazil |
| Oliveira, Jocy de (? - ) Brazil |
| Oliveira, Willy Corrêa de (1938 - ) Brazil |
| Oliver, Ángel (1937 - 2005) Spain |
| Oliver, Harold (1942 - ) U.S.A. |
| Oliver, John (1959 - ) Canada |
| Oliver, Stephen (1950 - 1992) United Kingdom |
| Olivero, Betty (1954 - ) Israel |
| Olives Palenzuela, Juan José (1951 - ) Spain |
| Olivoni, Davide (1963 - ) Italy |
| Olkusnik, Joachim (1927 - ) Poland |
| Ollertz, Ralf R. (1964 - ) Germany |
| Olm, Marcel (1932 - ) Spain |
| Olofsson, Jan Erik (1969 - ) Sweden |
| Olofsson, Kent (1962 - ) Sweden |
| Olsen, Morten (1961 - ) Denmark |
| Olsen, Poul Rovsing (1922 - 1982) Denmark |
| Olsen, Tim (1961 - ) U.S.A. |
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