Elizabeth Ollerton to Edward Oneil - 1881 Census household returns
- Elizabeth Ollerton to Richard Ollerton
- Robert Ollerton to George Ollett
- George P Ollett to Catherine Olley
- Charles Olley to George G Olley
- George H Olley to John Olley
- John Olley to Robert J Olley
- S A Olley to William Olley
- William Olley to George Ollier
- George Ollier to William Ollier
- William Ollier to Laura Olliffe
- Louisa Olliffe to William Ollington
- Mary Gray Ollins to Mary Ollis
- Nathaniel Ollis to Edward Ollivant
- Edward A Ollivant to Elizabeth Olliver
- Emily L Olliver to John Olliver
- John Olliver to Thomas Olliver
- Thomas Olliver to Henry Ollivier
- Jean Ollivier to Samuel Olner
- Thomas Olner to Frederick Olney
- George Olney to Jonathan Olney
- Joseph Olney to William Olney
- William Olney to John Olorenshaw
- John Olorenshaw to Alfred Olpin
- Charles J Olpin to Annie Olsen
- Antoni Olsen to Mons A Olsen
- Neils Olsen to George Olson
- George Olson to Alfred Oltrum
- John Oltshert to Hamilton Olver
- Harriet Olver to John J Olver
- John L H Olver to Thomas Olver
- Thomas Olver to John Olvey
- John Olvin to Alexander Oman
- Alexander Oman to James A Oman
- Jane Oman to William Oman
- George Omand to John Omara
- John Omara to Mary Omeara
- Ellen Omega to Lawrence Omerod
- Luke Omerod to Thomas Ommlish
- Adolph Ommundsen to William Oncil
- Mary Ann Oncill to Edward Oneil