Joseph Olley to John Oneil - 1911 Census household returns
- Joseph Olley to Robert Charles Olley
- Samuel Olley to William Olley
- William Olley to Edgar Ollier
- Edmund Ollier to James Ollier
- James Ollier to Samuel Ollier
- Samuel Ollier to James Olliff
- Leonard Olliff to Thomas F Olliffe
- Thomas Henry Olliffe to James Thomas Ollington
- James William Ollington to Ernest Ollis
- Florence Ollis to Thomas Edgar Ollis
- Thomas Edwin Ollis to Frances Ollive
- Frank Ollive to Edward Olliver
- Edward Olliver to John Olliver
- John Olliver to William Henry Olliver
- William Joseph Olliver to Lilian Ollsson
- Edward Ollwant to William George Olner
- William Olnet to Charles William Olney
- Daniel Norris Olney to Grace Ethel Olney
- Gutteridge Olney to Joseph Olney
- Joseph Olney to Violet Olney
- W Olney to Henry Olorenshaw
- Henry Olorenshaw to Margaret Olphert
- Margaret Anne Olphert to John Christine Olrog
- William James Olrog to Anthony Olsen
- Arthur E Olsen to David Olsen
- Dorothea R Olsen to Ingeborg Olsen
- Ingvald Olsen to Krestopher L Olsen
- L Olsen to Peter Olsen
- Peter Olsen to Albert Olson
- Albert Olson to Oliver Olson
- Olof Olson to Louis Olsson
- Olaf Olsson to Albert Charles Olver
- Albert Edward Olver to George A Olver
- George Frederick Olver to John Olver
- John Olver to Richard Olver
- Richard Olver to William Olver
- William Olver to Hannah Olwen
- George Olwer to Thomas Omalley
- Thomas Omalley to Simon Rust Oman
- Sinclair Oman to Charles Frank Ombler
- David Ombler to John Omelia
- Joseph Henry Omelia to Fred Omers
- Kladyslaw Omilanowski to Arthur H Omor
- Edward Omora to Daniel Oneil
- Edward Oneil to John Oneil