- O'Connor
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James 439 b. 1818Michael 3200 b. 1831Patrick 5354 b. 1832, d. 22 Apr 1861
- O'Dea
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Edmund 2025 b. 1825, d. 20 Apr 1906Edward 2025 b. 1825, d. 20 Apr 1906
- O'Donnell
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James 3585 b. 1838, d. 30 Nov 1911James 934 b. 1832John 1513 b. 1824Lawrence 2183 b. 1825Neil 8096 b. 1836William 3600 b. 1825
- O'Halloran
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John Maurice 2175 b. 1820
- O'Hara
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Felix 8952 b. 1834, d. 23 May 1910Henry 8378 b. 1837James 8379 b. 1839Michael 4045 b. 1837Michael 6147 b. 1838
- O'Hare
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Daniel 7223 b. 1804, d. 30 Jul 1873Felix 8952 b. 1834, d. 23 May 1910
- O'Lachlan
-
Roderick 8376 b. 1835
- O'Lochlan
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Roderick 8376 b. 1835
- O'Malley
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Anthony 4258 b. 1836, d. 21 Feb 1884
- O'Mara
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Cornelius 2176 b. 1828, d. 4 Jan 1911John 2530 b. 1830, d. 31 Dec 1915
- O'Neil
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James 4478 b. 1830John 4335 b. 1830John 5140 b. 1830Michael 4329 b. 1833Peter 7505 b. 1842, d. 10 Jun 1890Peter 8954 b. 1829Stephen 2591 b. 1830Terence 4391 b. 1832