| John Campbell White |
Overtoun, of Overtoun in the County of Dumbarton (Barony) |
Fri 23rd Jun 1893 |
Sat 15th Feb 1908 |
| Sydney Haldane Olivier |
Olivier, of Ramsden in the County of Oxford (Barony) |
Sat 9th Feb 1924 |
Mon 15th Feb 1943 |
| Herbert Henry Asquith |
of Oxford and Asquith (Earldom) |
Mon 9th Feb 1925 |
Wed 15th Feb 1928 |
| Raymond Benedict Bartholomew Michael Asquith |
of Oxford and Asquith (Earldom) |
Sun 16th Jan 2011 |
|
| Julian Edward George Asquith |
of Oxford and Asquith (Earldom) |
Wed 15th Feb 1928 |
Sun 16th Jan 2011 |
| Geoffrey Lawrence |
Oaksey, of Oaksey in the County of Wilts (Barony) |
Mon 13th Jan 1947 |
Sat 28th Aug 1971 |
| Patrick John Tristram Lawrence |
Oaksey, of Oaksey in the County of Wilts (Barony) |
Wed 5th Sep 2012 |
|
| John Geoffrey Tristram Lawrence |
Oaksey, of Oaksey in the County of Wilts (Barony) |
Sat 28th Aug 1971 |
Wed 5th Sep 2012 |
| David Rees Rees-Williams |
Ogmore, of Bridgend in the County of Glamorgan (Barony) |
Mon 10th Jul 1950 |
Mon 30th Aug 1976 |
| Gwilym Rees Rees-Williams |
Ogmore, of Bridgend in the County of Glamorgan (Barony) |
Mon 30th Aug 1976 |
Tue 9th Nov 2004 |
| Morgan Rees Rees-Williams |
Ogmore, of Bridgend in the County of Glamorgan (Barony) |
Tue 9th Nov 2004 |
Sat 2nd May 2020 |
| Tudor David Rees-Williams |
Ogmore, of Bridgend in the County of Glamorgan (Barony) |
Sat 2nd May 2020 |
|
| Terence Marne O'Neill |
O'Neill of the Maine, of Ahoghill in the County of Antrim (Barony) |
Fri 23rd Jan 1970 |
Tue 12th Jun 1990 |
| Laurence Kerr Olivier |
Olivier, of Brighton in the County of Sussex (Barony) |
Fri 5th Mar 1971 |
Tue 11th Jul 1989 |
| Charles Ian Orr-Ewing |
Orr-Ewing, of Little Berkhamsted in the County of Hertford (Barony) |
Fri 30th Apr 1971 |
Thu 19th Aug 1999 |
| Leslie Kenneth O'Brien |
O'Brien of Lothbury, of the City of London (Barony) |
Wed 14th Mar 1973 |
Fri 24th Nov 1995 |
| Albert Edward Oram |
Oram, of Brighton in the County of East Sussex (Barony) |
Thu 22nd Jan 1976 |
Sat 4th Sep 1999 |
| Peter Raymond Oliver |
Oliver of Aylmerton, of Aylmerton in the County of Norfolk (Barony) |
Fri 31st Jan 1986 |
Wed 17th Oct 2007 |
| Sally Oppenheim-Barnes |
Oppenheim-Barnes, of Gloucester in the County of Gloucestershire (Barony) |
Thu 9th Feb 1989 |
|
| Detta O'Cathain |
O'Cathain, of The Barbican in the City of London (Barony) |
Fri 21st Jun 1991 |
Fri 23rd Apr 2021 |