Senator Lifespan PartyC=Conservative, L=Liberal, LC=Liberal-Conservative, PC=Progressive Conservative. Prov. Entered Left Appointed by Left due to For life? James O'Brien 1836–1903 LC QC 2 January 1896 28 May 1903 Bowell Death Y Michael John O'Brien 1851–1940 C ON 1 September 1918 1 September 1925 Borden Resignation Y Frank Patrick O'Connor 1885–1939 C ON 6 December 1935 21 August 1939 King Death Y William Hunter Odell 1811–1891 C NB 23 October 1867 25 July 1891 Royal proclamation Death Y John O'Donohoe 1824–1902 LC ON 21 May 1882 7 December 1902 Macdonald Death Y Kelvin Ogilvie 1942–2025 C NS 27 August 2009 6 November 2017 Harper Retirement Victor Oh 1949–present C ON 25 January 2013 9 June 2024 Harper Retirement Clement O'Leary 1916–1969 PC NS 25 September 1962 12 June 1969 Diefenbaker Death Y Grattan O'Leary 1888–1976 PC ON 24 September 1962 7 April 1976 Diefenbaker Death Y Alexander Walker Ogilvie 1829–1902 C QC 24 December 1881 18 January 1901 Macdonald Resignation Y Donald Oliver 1938–2025 C NS 7 September 1990 16 November 2013 Mulroney Retirement Louis Auguste Olivier 1816–1881 C QC 23 October 1867 8 September 1873 Royal proclamation Resignation Y Bud Olson 1925–2002 C AB 5 April 1977 7 March 1996 Trudeau, P. Resignation Ratna Omidvar 1949–present NA ON 1 April 2016 5 November 2024 Trudeau, J. — Y Gigi Osler 1968–present MB 26 September 2022 — Trudeau, J. — Gerry Ottenheimer 1934–1998 PC NL 30 December 1987 18 January 1998 Mulroney Death Manuelle Oudar 1963–present QC 13 February 2024 — Trudeau, J. — Rodney Ouellette ?–present NB 7 July 2026 — Carney — William Owens 1840–1917 C QC 2 January 1896 8 June 1917 Bowell Death Y