- Ô Canada!
- Ô Canada! mon pays! mes amours!
- O'Brien, Lucius Richard
- O'Brien, Michael John
- O'Brien, Oscar
- O'Donnell, John
- O'Donoghue, Daniel John
- O'Grady, Standish
- O'Grady, William John
- O'Hara, Geoffrey
- O'Leary
- O'Leary, Michael Grattan
- O'Neil, Jean
- O'Neill, Charles
- O'Neill, Thelma
- O'Reilly, Gerald
- O'Sullivan, Shawn
- O. Croteau
- O. Hindsgaul
- O. P. Dwivedi
