Komponisten der Gegenwart (KDG) O-Ph
- Obst, Michael
- Obuchov, Nikolaj
- Odriozola, Ricardo
- Oehring, Helmut
- Ofenbauer, Christian
- Ohana, Maurice
- Olah, Tiberiu
- Olbrisch, Franz Martin
- Oliveros, Pauline
- Oña, Erik
- Ono, Yoko
- Orellana, Joaquín
- Ornstein, Leo
- Osborne, Nigel
- Ospald, Klaus
- Ostendorf, Jens-Peter
- Ostertag, Bob
- Ostrčil, Otakar
- Ott, Daniel
- Otte, Hans
- Pablo Costales, Luis de
- Pärt, Arvo
- Pagh-Paan, Younghi
- Paik, Byung-Dong
- Palester, Roman
- Pan, Hwang-Long
- Panufnik, Andrzej
- Paraskevaídis, Graciela
- Partch, Harry
- Paz, Juan Carlos
- Peixinho, Jorge
- Penderecki, Krzysztof
- Pepping, Ernst
- Petersen, Wilhelm
- Petrassi, Goffredo
- Pettersson, Allan
- Petyrek, Felix
- Pfitzner, Hans
- Pflüger, Hans Georg