- Ornithomimus
- Oromocto
- Oronhyatekha
- Orpha-F Deveaux
- Orphan Black
- Orpheum Theatre (Vancouver)
- Orpheum Theatre
- Orpheum Theatre (Montréal)
- Orpheus Choir of Toronto
- Orpheus Club
- Orpheus Club of Halifax
- Orpheus Musical Theatre Society of Ottawa
- Orthodox Church
- Canadian Soldiers and the Battle of Ortona
- Orval Prophet