NameElected partyConstituencyElected dateMilitary serviceWilliam O'BrienConservativeMuskoka and Parry SoundJune 20, 1882Militia (1885)Martin Patrick O'ConnellLiberalScarborough EastJune 25, 1968Canadian Forces Land Force CommandGordon O'ConnorConservativeCarleton—LanarkJune 28, 2004Canadian Forces Land Force CommandJohn Francis O'ReillyLiberalVictoria—HaliburtonOctober 25, 1993Canadian Army (1955-1957)Horace Andrew "Bud" OlsonSocial CreditMedicine HatJune 10, 1957Canadian ArmyJohn Martin OostromProgressive ConservativeWillowdaleSeptember 4, 1984Royal Netherlands Air Force (1950-1951)Robert OrangeLiberalNorthwest TerritoriesNovember 8, 1965Royal Navy (1945)James Norris OrmistonProgressive ConservativeMelvilleMarch 31, 1958Canadian Army (1939-1946)Edmund Boyd OslerLiberalWinnipeg South CentreJune 25, 1968Royal Canadian Air Force (1940-1945)Joseph-Aldric OuimetLiberal-ConservativeLavalOctober 28, 1873Militia