| Australia | O'Hara associations with Australia; O'Haras in Australia |
| Barbados | O'Hara associations with Barbados ; O'Haras in Barbados |
| Belgium | O'Hara associations with Belgium; O'Haras in Belgium |
| Canada | O'Hara associations with Canada; O'Haras in Canada |
| China | O'Hara associations with China; O'Haras in China |
| Czech Republic | O'Hara Czech associations ; O'Haras in the Czech Republic |
| France | O'Hara associations with France; O'Haras in France |
| Germany | O'Hara associations with Germany; O'Haras in Germany |
| Gibraltar | O'Hara associations with Gibraltar; O'Haras in Gibraltar |
| Honduras | O'Hara associations with Honduras ; O'Haras in Honduras |
| India | O'Hara associations with India; O'Haras in India |
| Ireland by county | O'Hara associations with the Irish counties |
| Republic of Ireland | O'Hara associations with Ireland; O'Haras in Ireland |
| Northern Ireland | Northern Irish O'Haras; O'Haras in Northern Ireland |
| Japan | O'Hara associations with Japan; O'Haras in Japan |
| Mexico | O'Hara associations with Mexico; O'Haras in Mexico |
| New Zealand | O'Hara associations with New Zealand ; O'Haras in New Zealand |
| Philippines | O'Hara associations with the Philippines ; O'Haras in the Philippines |
| Romania | O'Hara associations with Romania ; O'Haras in Romania |
| Russia | O'Hara associations with Russia; O'Haras in Russia |
| Singapore | O'Hara associations with Singapore ; O'Haras in Singapore |
| Spain | O'Hara associations with Spain; O'Haras in Spain |
| Sweden | O'Hara associations with Sweden; O'Haras in Sweden |
| United Kingdom | O'Hara associations with the UK; O'Haras in the UK |
| USA | O'Hara associations with the USA; O'Haras in the USA |