Family History and Genealogy Resources by Surname
McGrath Surname Origin
(Origin Celtic or Gaelic) From Gradh, love, fondness, virtue, prosperity. Mac and rath, the son of prosperity.
Source: An Etymological Dictionary of Family and Christian Names With an Essay on their Derivation and Import; Arthur, William, M.A.; New York, NY: Sheldon, Blake, Bleeker & CO., 1857.
McGrath Surname Meaning and Family Facts
There is more to McGrath family history than the origin of your surname:
A McGrath Family History Thought:
'The past isn't dead. It isn't even past.' --William Faulkner