Ó hAimheirgin
Ó hAIMHEIRGIN, Ó hAIMHIRGIN—I—O Havergan, O Hemergin, Mergin, Bergin, Bergen, Bergan, Berrigan, &c.; 'descendant of Aimhirgin' (wondrous birth); the name of an Offaly family who were formerly chiefs of the barony of Geashill; still common in Leinster, but long corrupted to Ó Meirgin and Ó Beirgin, which see.
Alphabetical Index to Irish Surnames