Ødegaard, Henrik (b. 1955)
O'Donnell, John (b. 1948)
Oehring, Helmut (b. 1961)
Ogasapian, John (1940-2005)
Ogden, Nigel (b. 1954)
Oguri, Katsumi (b. 1962)
Ohse, Rheinhard (b. 1930)
Olaizola Gabarain, José de (1883-1969)
Olczak, Krzysztof (b. 1956)
Oldenbeuving, Gert (b. 1946)
Oldham, Kevin (1960-1993)
Oldroyd, George (1886-1951)
Oliveira, João Pedro  (b. 1959)
Olivera, Hector (b. 1946)
Olivier, Gerrit (b. 1945)
Ollive, Serge (b. 1977)
Olsen, Sparre (1903-1984)
Olson, Daniel (1898-1978)
Olsson, Otto (1879-1964)
O'Neill, Nicholas (b. 1970)
Opsjön, Oddmund (b. 1956)
Ollive, Serge (b. 1977)
Ore, Ādams (1853-1927)
O’Regan, Tarik (b. 1978)
Orlinski, Heinz (b. 1928)
Orr, Robin (1909-2006)
Orrego, Juan (b. 1919)
Orthel, Léon (1905-1985)
Osada, Ryszard (b. 1972)
Osieck, Hendrik (Hans) (1910-2000)
Osterman, Eurydice  
Oswald, Henrique (1852-1931)
Otto, Hans (1922-1996)
Ouellette, Antoine (b. 1960)
Owen, Harold (b. 1931)
Owens, Rebecca Kleintop