Murphy (51) Mac Murchaidh. The name Murchadh means 'Sea Warrior / Hound'. The Murphys of South Ulster where originally Mac Murchaidh (pronounced 'A' Wurfee' in Omeath).
Morgan (49) Ó Muireagáin. Can be a Welsh name but it can been used to anglicise a number of Irish surnames including Ó Murcháin agus Ó Muireagáin. The evidence points to Morgan being used to anglicise Ó Muireagáin in South Down and in South Armagh. Pron. "ă mŭr′-ă-Găan" in S Armagh (SÓhA via Ó Duibhín).
Fitzpatrick (46) Mac Giolla Phádraig. "The only Fitz name of Gaelic-Irish origin" according to MacLysaght. Mac Giolla Phádraig means 'son if a devotee of St. Patrick'.
O'Hagan (43) Ó hAgáin. Two distinct Gaelic surnames have been anglicised as O'Hagan. Ó hAgáin which is a venacular form of Ó hÓgáin and Ó hAodhagáin 'descendent of little Aodh'.
McPoland (35) Mac Póilín (pron. Mac Póilin) The McPolins originally anglicised their name to 'Poland' but this form went out of fashion. The name means 'son of little Paul'.
Grant (33) Mac Gránna. Whilst Grant is normally of Scottish origins in Ulster and commonly thought off as a non native name and occasionaly gaelicised as de Grannd. However, the evidence suggested that the Grants of South Down are Mac Gránna, pronounced 'wah-Graa′-nă' in South Armagh were it is anglicised as McGrane.
Branagan (22) Ó Branagáin. Ó Branagáin means 'descendent of little Bran'. Bran means 'raven'.
Fagan (22) Ó Faodhagáin. More commonly anglicised as Fegan in Clonduff today. Ó Faodhagáin means 'son of little Aodh'.
Brady (21) Mac Brádaigh. Mac Brádaigh means 'son of Brádach'
McGinn (19) Mag Fhinn. Mag Fhinn means 'son of Fionn'. Fionn meaning 'fair-haired'.