Donald O'Brien may refer to:
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Donald O'Brien (actor)
Donal "Donald" O'Brien (15 September 1930 – 29 November 2003) was an Irish film actor, film and television actor. In his near 40-year career, O'Brien appeared in dozens of stage performances and in more than 60 film and television productions. ...
(1930–2003), French-born Italian film and television actor
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Donald E. O'Brien (1923–2015), U.S. district judge
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Domnall Mór Ua Briain
Domnall Mór Ua Briain, or Domnall Mór mac Toirrdelbaig Uí Briain, was King of Thomond in Ireland from 1168 to 1194 and a claimant to the title King of Munster. He was also styled King of Limerick, a title belonging to the O'Brien dynasty ...
(died 1194), King of Thomond in Ireland (1168–1194)
{{hndis, Obrien, Donald