Leahy is an Irish surname, originating in Munster, and now found in Cork, Kerry, Limerick, and Tipperary. Anglicised from the Irish Gaelic Ó Laochdha ('descendant of Laochdha'), it ultimately derives from Old Irish láechda, láech ('warrior-like, pertaining to a warrior') which appears as a personal sobriquet at least as early as the Book of Lismore.
Other forms of the name include Lahey, Lahy, Leehy, and (less commonly) Lahaie, Lahaye, Lehait, Ó'Lathaigh.
Notable bearers of the name
References
Leahy (surname) Wikipedia(Text) CC BY-SA