- MORRIS, THOMAS (1761 - 1831), bootmaker - see MORRIS, WILLIAM
- MORRIS, VALENTINE (1727 - 1789), colonial administrator and landowner
- MORRIS, WILLIAM (fl. 1829-1873?), assistant to the Education Commissioners of 1846-7
- MORRIS, WILLIAM (1705 - 1763), botanist, antiquary, letter-writer
- MORRIS, WILLIAM (c. 1816? - 1886), printer and publisher of books and periodicals of Anglican interest
- MORRIS, WILLIAM (1783 - 1861), Calvinistic Methodist minister
- MORRIS, WILLIAM (Rhosynnog; 1843 - 1922), Baptist minister
- MORRIS, WILLIAM (1758 - 1808) Llanfeugan - see MORRIS, LEWIS
- MORRIS-JONES, Sir JOHN (MORRIS) (1864 - 1929), scholar, poet, and critic
- MORRIS-JONES, JOHN HENRY (1884 - 1972), Liberal\/National Liberal politician
- MORTIMER family Wigmore,
- MORTIMER, Earls of - see HARLEY
- MORTIMER, ROGER de (4th earl of March, 4th earl of Ulster), (1374 - 1398)
- MORTIMER, ROGER de (1256? - 1326), lord of Chirk
- MORTON, RICHARD ALAN (1899 - 1977), biochemist
- MORUS ap DAFYDD ab IFAN ab EINION - see MORUS DWYFECH
- MORUS ap LLYWELYN - see MORUS MAWDDWY
- MORUS BERWYN (fl. c. 1553-1615), poet
- MORUS DWYFECH (fl. c. 1523-1590), a poet
- MORUS GETHIN (fl. c. 1525), poet
- MORUS MAWDDWY (fl. c. 1540-1570), poet
- MORYS ap HYWEL (ap TUDUR) (fl. c. 1530), a poet
- MORYS, HUW (Eos Ceiriog; 1622 - 1709), poet
- MOSES, DAVID LEWIS - see MOSES-EVANS, DAVID LEWIS
- MOSES, EVAN (1726 - 1805) Trevecka, a tailor
- MOSES, WILLIAM (Gwilym Tew o Lan Tâf, Gwilym Tew; 1742 - 1824), poet
- MOSES-EVANS, DAVID LEWIS (1822 - 1893), poet and schoolmaster
- MOSS, GWENFRON (1898 - 1991), missionary in China and India
- MOSSELL, AARON ALBERT (1863 - 1951), lawyer, mining engineer and civil rights campaigner
- MOSTYN family Mostyn Hall,
- MOSTYN family Talacre,
- MOSTYN, 1st Baron - see MOSTYN
- MOSTYN, 2nd Baron - see MOSTYN
- MOSTYN, AMBROSE (1610 - 1663), a Puritan preacher
- MOSTYN, Baron WILLIAMS of - see WILLIAMS, GARETH WYN
- MOUNT-EARL, Viscount - see WYNDHAM-QUIN, WINDHAM HENRY
- MUNGO - see KENTIGERN
- MUTTON, Sir PETER (1565 - 1637), judge and politician
- MYDDELTON family Gwaenynog,
- MYDDELTON, WILIAM - see MIDLETON, WILIAM
- MYDDLETON, Gwaenynog - see MYDDELTON
- MYFYR EIFION - see HUGHES, DAVID ROWLAND
- MYFYR EMLYN - see THOMAS, BENJAMIN
- MYFYR HEFIN - see BOWEN, DAVID
- MYFYR MORGANWG - see DAVIES, EVAN
- MYFYR WYN - see WILLIAMS, WILLIAM
- MYLLIN - see JONES, JOHN
- MYNORYDD - see DAVIES, WILLIAM
- MYNYDDOG - see DAVIES, RICHARD
- MYRDDIN FARDD - see JONES, JOHN