Wikipedia
O'Halloran
O'Halloran (also O'Halleron, Halloran, Haloran, and in Irish, Ó hAllmhuráin or '' Ó hAlluráin'') is the surname of a Gaelic- Irish family. The name roughly translates as 'from beyond the sea.' The family motto is 'Clann Fearghaile Abú.' This comes from the Galway branch, clann Fhergail (the family of the men of the foreigner), whose territory was extensive around Lough Corrib.
The name originates from County Clare and County Galway, with the Clare branch having links with the Dál gCais clan.