O'brien Family History
O'brien Name Meaning
Irish: Anglicized form of Gaelic Ó Briain ‘descendant of Brian’, a personal name probably based on the element bre- ‘hill’, with the transferred sense ‘eminence’, i.e. ‘exalted one’. See also Bryan. In Ireland there has also been some confusion with O’Byrne (see Byrne).
Source: Dictionary of American Family Names ©2013, Oxford University Press