Halleran
Irish: variant of Halloran.
Dictionary of American Family Names, Oxford University Press, ISBN 0-19-508137-4
Halloran
Irish: shortened Anglicized form of Gaelic Ó hAllmhuráin ‘descendant of Allmhurán’, a personal name from a diminutive of allmhurach ‘foreigner’ (from all ‘beyond’ + muir ‘sea’).
Dictionary of American Family Names, Oxford University Press, ISBN 0-19-508137-4
O'Halloran
Irish: Anglicized form of Gaelic Ó hAllmhuráin ‘descendant of Allmhurán’ (see Halloran).
Dictionary of American Family Names, Oxford University Press, ISBN 0-19-508137-4