Name
- McDonogh, Eamon1
- McGuire, Thomas1
- McGuire, William1
- McMorris, John1
- Merddin ab Morvryn, alias Merddin Wylt1
- Meyer, Kuno, Professor of Celtic, Berlin1
- Mils, Dr1
- Moeran, Ernest John, composer, 1894-19501
- Molaisse, Saint, Founder of Devenish Monastery in Lough Erne1
- Molloy, Cormac, weaver of Glencolumcille Donegal1
- Morgan, James, of Add MS 149351
- Morgan, John, Reverend; of Add MS 148661
- Morris, Lewis, alias Llywelyn Ddu1
- Morris, Richard, alias Rhisiart Fynglwyd, alias Llewelyn Ddulwyd1
- Mortimer, Family1
- Mortimer, Roger, of Add MS 149351
- Murphy, John, of Reheenagh, county Cork1
- Nagle, Edward, of Cork1
- Neeson, Sean, of Cork1
- Nugent, Nicholas, Chief Justice of the Common Pleas, Ireland1