Lucius O'Brien may refer to:
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Lucius O'Brien (died 1717)
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Sir Lucius O'Brien, 3rd Baronet (1731–1795), Member of the Parliament of Ireland
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Lucius O'Brien, 13th Baron Inchiquin (1800–1872), Irish politician and nobleman
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Lucius O'Brien, 15th Baron Inchiquin
Lucius William O'Brien, 15th Baron Inchiquin (21 June 1864 – 9 December 1929) was the England-born holder of a hereditary peerage in the Peerage of Ireland, as well as Chief of the Name of O'Brien and Prince of Thomond in the Gaelic Irish ...
(1864–1929)
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Lucius Richard O'Brien (1832–1899), Canadian painter
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Lucius O'Brien (priest) (1842–1913), Dean of Limerick in the Church of Ireland
{{hndis, Obrien, Lucius