Morgan
Welsh: from the Old Welsh personal name Morcant, which is of uncertain but ancient etymology.
Irish: importation of the Welsh surname, to which has been assimilated more than one Gaelic surname, notably Ó Muireagáin (see Merrigan).
Scottish: of uncertain origin; probably from a Gaelic personal name cognate with Welsh Morcant.
Merrigan
Irish: Anglicized form of Gaelic Ó Muireagáin ‘descendant of Muireagán’ a personal name representing a name beginning with muir ‘sea’. Earlier found in the Irish midlands and southern Ulster, this surname is now found throughout Ireland.