Oakes - Owen
- Edward Oakes (1770-1838)
- William Longden Oakes (1886-1972)
- William Oates (1841-1906)
- Catherine O'Bryan (fl.1831)
- Mary O'Bryan (1807-83)
- William O'Bryan (1778-1868)
- James Oddy (c.1730-90)
- James Odgers (1773-1855)
- Hallifield Cosgayne O'Donnoghue (1789-1842)
- James Edward Oglethorpe (1696-1785)
- James Oke (d.1833)
- Francis Okely (1719-1794)
- John Okely (1721-1792)
- John Oliver (b.1789)
- Thomas Perry Oliver (1822-93)
- Thomas Olivers (1725-99)
- John Orchard (1838-1907)
- George Osborn (1808-91)
- George Robson Osborn (1905-79)
- Richard Henry Osborne (1873-1951)
- Gideon Ouseley (1762-1839)
- John Owen (fl.1773)
- Samuel Owen (1777-1840)