- Otto Jacobi
- Otto Joachim
- Otto P. Strausz
- Otto-Werner Mueller
- Ouchterlony, David
- Ouellet, Fernand
- Ouellette, Fernand
- Ouellette-Michalska, Madeleine
- Ouimet, Gédéon
- Ouimet, Joseph-Alphonse
- Ouimet, Léo-Ernest
- Ounanguissé
- Oundjian, Peter
- Our Best and Brightest, Now Forgotten
- Our Dying Seas
- Our Health Care Delusion
- Our Home and Native Tongue
- Our Lady Peace
- Our Lady Peace
- Our Orchestral One-night Stands