- O'Brien
- O'Hanly
- O'Leary
- Oak Bay
- Oak Bay
- Oak Bay
- Oak Bluff
- Oak Haven
- Oak Lake
- Oak Orchard
- Oak Point
- Oak River
- Oakbank
- Oakburn
- Oakdale
- Oakdale
- Oakland
- Oakland
- Oakview
- Oakview Beach
- Oakville
- Oakville
- Oakwood
- Oba
- Oban
- Obaska
- Obed
- Obedjiwan
- Obiduan
- Ocean Falls
- Ochiltree
- Ochre River
- Oconnor
- Oconto
- Odanah
- Odanak
- Oderin
- Odessa
- Odessa
- Ogden
- Ogema
- Ogilvie
- Ogoki
- Ohaton
- Ohsawa
- Ohsweken
- Oil City
- Oil Springs
- Oka
- Okanagan
- Okanagan Centre
- Okanagan Falls
- Okanagan Landing
- Okanagan Mission
- Okanagan-Similkam
- Okanagan-Similkameen
- Okla
- Okotoks
- Olalla
- Old Chelsea
- Old Crow
- Old Factory River
- Old Fort
- Old Fort Bay
- Old Hogem
- Old Montreal
- Old Perlican
- Old Post
- Old Wives
- Oldcastle
- Olds
- Oleary
- Olha
- Olinda
- Oliphant
- Oliver
- Oliver Paipoonge
- Omemee
- Omerville
- Ompah
- Onanole
- Onaping
- Onaping Falls
- One Hundred Fifty Mile House
- One Hundred Mile House
- Onefour
- Oneida
- Onion Lake
- Onoway
- Oona River
- Ootischenia
- Ootsa Lake
- Opal
- Opasatika
- Opaskwayak
- Opasquia
- Open Hall
- Ophir
- Opishing Lake
- Orangedale
- Orangeville
- Ordale
- Orford
- Orford Twp
- Orient Bay
- Orillia
- Orillia Township
- Orion
- Orkney
- Orkney Beach
- Orland
- Orleans
- Ormiston
- Ormond
- Ormsby
- Ormstown
- Oro
- Oro Medonte
- Oro Station
- Oro-Medonte
- Oromocto
- Oromocto Nb
- Orono
- Orr Lake
- Orrville
- Orton
- Orwell
- Osaca
- Osage
- Osborne
- Osceola
- Osgoode
- Oshawa
- Oskelaneo
- Osland
- Osler
- Osnabruck Centre
- Osnaburgh House
- Osoyoos
- Oswego Park
- Otis
- Otonabee Twp
- Otonabee-South Monaghan
- Ottawa
- Otter
- Otter
- Otter Creek
- Otter Lake
- Otter Lake
- Otterburn Park
- Otterburn-Park
- Otterburne
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- Ouellette
- Ouest de l'ile - Montreal
- Ouiatchouan
- Ouimet
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- Outlet
- Outlook
- Outlook
- Outram Station
- Ouvry
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- Owen Sound
- Owl River
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- Oxbow
- Oxbow Lake
- Oxdrift
- Oxenden
- Oxford
- Oxford Centre
- Oxford House
- Oxford Junction
- Oxford Mills
- Oxford Station
- Oxley
- Oxley Beach
- Oxtongue Lake
- Oyama
- Oyen
- Oyster Bay