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- Maggie Blue O'Hara – singer, actress, voice artist
- Mary Margaret O'Hara – pop/rock singer-songwriter
- Melissa O'Neil – pop singer (winner of Canadian Idol 2005)
- Mike O'Neill - singer, songwriter and guitarist (The Inbreds)
- Nivek Ogre - industrial rock singer
- Oh Susanna – alternative country singer
- Jenny Omnichord — indie pop singer-songwriter
- Moka Only - rapper
- Maren Ord – pop singer
- Achilla Orru - lukembé player
- Lindi Ortega - singer-songwriter
- Walter Ostanek – polka musician and accordionist
- John Oswald – composer
- Peter Oundjian – violinist and conductor
Read more about this topic: List Of Canadian Musicians