Mag Eacháin
Mag EACHÁIN—IV—M'Geaghan, MacGahan, Magahan, Megahan, (Magan, Magann), Geghan, Gaughan, Gahan; 'son of Eachán' (a diminutive of Eachaidh); a variant of Mac Eacháin and Mag Eocháin, which see. It appears to have been sometimes used in the midlands as an alias for Mac Eochagáin, which see.
Alphabetical Index to Irish Surnames