Family History and Genealogy Resources by Surname
O'Leary Surname Origin
The descendant of Lary; Llary, Welsh, gentle, easy.
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.
O'Leary Surname Meaning and Family Facts
There is more to O'Leary family history than the origin of your surname:
A O'Leary Family History Thought:
Whenever there's a will, you'll see an heir loom.