| Mackie | Scotland | Mid-Lothian | Portobello | 1800 - 1890 | 7045 | 1261 | ||
| Mailieu | Ireland | Tyrone | Arny | Pre 1835 | 10951 | 1319 | ||
| Main | Scotland | Lanarkshire | Airdrie | Airdrie | pre 1800 | 4889 | 625 | |
| Malone | Ireland | Clare | Tuamgraney | 1800 - | 13547 | 1346 | ||
| Maloney | Ireland | Kilkenny | -1830 | 8686 | 651 | |||
| Marre | Scotland | Perthshire | Kinnoul | 1600 | 3487 | 897 | ||
| Martin | Ireland | Antrim | Tavanghmore | Grange of Shilvodan | Tavnaghmore | pre 1797 | 8049 | 750 |
| Martin | Ireland | Down | Dromara | 1790 - 1830 | 3935 | 366 | ||
| Martin |
Ireland |
Killedmond |
1820 - 1855 |
13164
|
1241
|
|||
| Martin |
Ireland |
Co Carlow |
Clogherny |
Seskinone |
1820 - 1855 |
13164
|
1242
|
|
| Martin |
Ireland |
Carlow |
Banory - Idrone east |
Kiltennell |
Killedmand |
1780 - 1870 |
13164
|
1244 |
| Martin | Scotland | Wigtown | Withorn | 1860 + | 3935 | 358 | ||
| Martin | Scotland | Ayrshire | Colmonell | Barrhill | 1830 - 1860 | 3935 | 357 | |
| Mason | Scotland | Aberdeen | Peterculter | 1800 's | 10126 | 1097 | ||
| Maxwell | Scotland | Stirling | Larbert | 1737 | 13547 | 1338 | ||
| Maxwell | Scotland | Stirling | Polmont | 1767 | 13547 | 1341 | ||
| McAntosh | Scotland | Perthshire | Kinnoul | 1706 | 3487 | 892 | ||
| McArdle | Scotland | Ullapool | 1800 - 1900 | 5556 | 1265 | |||
| McArthur | Scotland | Fife | Auchtermuchty | 1700 - | 11978 | 1301 | ||
| McClellan | Ireland | Derry | Ballyeglish | pre 1871 | 5406 | 703 | ||
| McClelland | Ireland | Down | Kilkeel | 1800 - 1899 | 1658 | 194 | ||
| McClurg | Ireland | Down | Knockbreda | Ballymacarrett | 1800 - | 6824 | 1157 | |
| McConvill | Ireland | Down | 1790 - 1838 | 12068 | 1294 | |||
| McConville | Ireland | Down | 1790 - 1855 | 12068 | 1293 | |||
| McDonald | Ireland | Antrim | 1820 - | 6824 | 1154 | |||
| McDonald | Scotland | Inverness | Glengarry | Leek | 1850 - 1860 | 2876 | 858 | |
| McDonald | Ireland | Tyrone | Longfield | 1813 - | 12349 | 1367 | ||
| McDonald | Ireland | Clare | -1854 | 12358 | 1178 | |||
| McEwan | Scotland | Perthshire | Kilmadock | 1770 | 3487 | 98 | ||
| McGarvey | Ireland | Fermanagh | Tomregan | 1800 - 1899 | 1658 | 196 | ||
| McInnes | Scotland | Invernesshire | Kilmorack | 6824 | 1164 | |||
| McIntyre | Scotland | Lanarkshire | Glasgow | 1800 - 1899 | 1658 | 782 | ||
| McIntyre | Scotland | Argyll | Inveraray | 1800 - 1899 | 1658 | 1309 | ||
| Mcintyre | Scotland | Bute | Rothesay | 1800 - 1899 | 1658 | 781 | ||
| McIssack | Scotland | Mor | Elgin | 1500 - 1700 | 2968 | 352 | ||
| McIvor | Ireland | Armagh | 1830 's | 12660 | 1375 | |||
| McKegear | Scotland | Glasgow | any time | 8958 | 953 | |||
| McKegear | Ireland | any time | 8958 | 951 | ||||
| McKelvie | Scotland | Ayrshire | Coylton | -1785 | 3935 | 361 | ||
| McKenna | Ireland | Antrim | Tavnaghmore | Grange of Shilvodan | Tavnaghmore | pre 1798 | 8049 | 749 |
| McKenzie | Scotland | Isle of Skye | 1805 - 1837 | 12349 | 1371 | |||
| McKinnon | Scotland | Kilmon : Vaig | 1800 | 12660 | 1380 | |||
| McKissack | Scotland | Mor | Elgin | 1500 - 1700 | 2968 | 351 | ||
| Mcleish | Scotland | Perthshire | Caputh | 1780 - 1880 | 2876 | 855 | ||
| McLellan | Ireland | Down | Kilkeel | 1800 - 1899 | 1658 | 195 | ||
| McLelland | Scotland | Ayr | St.Quivoa | 1807 + | 10126 | 1093 | ||
| McLelland | Scotland | Lanarkshire | Milton | Glasgow | 1871 + | 5406 | 696 | |
| McLelland | Scotland | Midlothian | Edinburgh | 1841 + | 10126 | 1092 | ||
| McLelland | Scotland | Ayr | Kirkmichael | 1755 + | 10126 | 1325 | ||
| McManus | Ireland | Cavan | -1854 | 12358 | 1144 | |||
| McMenamin | Ireland | Meenakeeran | Termonamongan | 1800 - 1828 | 13547 | 1343 | ||
| McMennemin | Ireland | Tyrone | -1828 | 13547 | 1326 | |||
| McMennemin | Ireland | Tyrone | Meenakeeran | Termonamongan | 1800 - 1828 | 13547 | 1342 | |
| McMillan | Scotland | Tarbolton | 1800 - 1865 | 10976 | 1289 | |||
| McNamara | Ireland | Clare | pre 1853 | 8049 | 753 | |||
| McNeilly | Ireland | 1824 - | 12349 | 1368 | ||||
| McNichol | Ireland | Armagh | Ardress | Loughgall | 1800 - 1872 | 3416 | 214 | |
| McNichol | Ireland | Armagh | Loughgall | Ardress | 1800 - 1872 | 3416 | 321 | |
| McNicholl | Scotland | Anywhere | Anytime | 3416 | 331 | |||
| McNickle | Ireland | Armagh | Ardress | Loughgall | 1800 - 1872 | 3416 | 215 | |
| McNickle | Ireland | Armagh | Loughgall | Ardress | 1800 - 1872 | 3416 | 322 | |
| McSkimmin | Scotland | Ayrshire | Ayr/Coylt | -1800 | 3935 | 360 | ||
| McWhirter | Scotland | Wigtown | Stonykirk | 1750 - 1900 | 12068 | 1295 | ||
| Middleton | Scotland | Fifeshire | Inverkeithny | 1832 | 8686 | 638 | ||
| Millar | Scotland | Angus | Montrose / Dundee | 1790 - | 13410 | 1321 | ||
| Millar | Scotland | Perth | Perth | 1790 - | 13410 | 1323 | ||
| Miller | Scotland | Orkney | Eday / Stronsay | Pre 1855 | 12003 | 1115 | ||
| Miller | Scotland | Stirling | 1798 | 13547 | 1340 | |||
| Milne | Scotland | Banff | Inverkeithny | 1872 | 8686 | 777 | ||
| Milne | Scotland | Aberdeen | Turriff | 1873 + | 8686 | 778 | ||
| Milne | Scotland | Mor | FocHabers | 1500 - 1700 | 2968 | 350 | ||
| Mitchell | Scotland | Abereen | Traves | 1700 - 1880 | 6056 | 889 | ||
| Mitchell | Scotland | Aberdeen | Olddeer | 1700 - 1880 | 6056 | 887 | ||
| Mitchell | Scotland | Abereen | Newdeer | 1700 - 1880 | 6056 | 886 | ||
| Mitchell | Scotland | Abereen | Longside | 1700 - 1880 | 6056 | 888 | ||
| Mitchell | Ireland | Carlow | Carlow | 1885 - 1915 | 6056 | 891 | ||
| Mitchell | Ireland | Laois / Queens | Clonmore | Rathdowney | Errill | 1600 - | 6824 | 1158 |
| Mitchell | Scotland | Abereen | Udny | 1700 - 1880 | 6056 | 890 | ||
| Moir | Scotland | Perthshire | Perth | 1748 | 3487 | 893 | ||
| Moir | Scotland | Perthshire | Kilmadock | 1770 | 3487 | 97 | ||
| Monaghan | Ireland | Galway | Monivea | 1830 - 1866 | 11445 | 1223 | ||
| Monaghan | Ireland | Galway | 1840 | 12660 | 1376 | |||
| Moore | Ireland | Down | Burren | Dromara | 1770 - | 6824 | 1155 | |
| Moore | Ireland | Down | Finnis | 1770 - | 6824 | 1156 | ||
| Moore | Ireland | Armagh | Loughgall | Ardress | 1800 - 1872 | 3416 | 323 | |
| Moore | Scotland | Lanarkshire | Old Monkland | Coatbridge | 1854 - | 6824 | 1167 | |
| Morris | Ireland | Galway | Monivea | 1830 - 1866 | 11445 | 1224 | ||
| Morris | Ireland | Tipperary | 1800 - | 6058 | 1273 | |||
| Morrison | Ireland | Dublin | 1851 | 8686 | 630 | |||
| Morrison | Scotland | Banff | Inverkeithny | 1777 - 1794 | 8686 | 764 | ||
| Morrison | Scotland | Lanarkshire | Hutchenso | Glasgow | 1870 | 8686 | 644 | |
| Morrison | Scotland | Mid Lothian | St Cuthbert | Edinburgh | 1881 | 8686 | 640 | |
| Morrison | Ireland | Dublin | 1860 | 8686 | 632 | |||
| Morrison | Scotland | Aberdeen | Old Machar | Aberdeen | 1858 | 8686 | 643 | |
| Morrison | Scotland | Aberdeen | Fetteress | Stonehaven | 1858 | 8686 | 642 | |
| Morrison | Scotland | Fifeshire | Inverkeithny | 1832 | 8686 | 637 | ||
| Morrison | Scotland | Aberdeen | St Nichol | Aberdeen | 1870 | 8686 | 645 | |
| Morrison | Scotland | Banff | Inverkeithny | 1850 - 1911 | 8686 | 768 | ||
| Morrison | Scotland | Aberdeen | Auchterless | Mains of Hatton | 1721 - 1870 | 8686 | 810 | |
| Morrison | Scotland | Aberdeen | Auchterless | Moat | 1750 - | 8686 | 811 | |
| Morrison | Scotland | Fife | Kinghorn | Kinghorn | 1805 + | 7006 | 874 | |
| Morrison | Scotland | Fife | Inverkeithing | Hillend | 1805 - 1875 | 7006 | 873 | |
| Morrison | Scotland | Aberdeen | Auchterless | Upper Mill | 1810 - 1830 | 8686 | 809 | |
| Morrison | Scotland | Aberdeen | Auchterless | Thorneybank | 1800 - 1860 | 8686 | 808 | |
| Morrison | Scotland | Banff | Inverkeithny | 1820 - 1847 | 8686 | 770 | ||
| Morrison | Scotland | Banff | Inverkeithny | 1820 - 1833 | 8686 | 767 | ||
| Morrison | Scotland | Aberdeen | Turriff | 1850 - 1900 | 8686 | 797 | ||
| Morrison | Scotlnad | Banff | Inverkeithny | 1820 - 1833 | 8686 | 800 | ||
| Morrison | Scotland | Aberdeen | Forglen | Penelopefield | 1850 - 1902 | 8686 | 806 | |
| Morrison | Scotland | Banff | Inverkeithny | 1850 - 1911 | 8686 | 801 | ||
| Morrison | Scotland | Lanarkshire | Glasgow | 1855 | 8686 | 773 | ||
| Morrow | Ireland | Tyrone | Dungannon | Pre 1778 | 10951 | 1318 | ||
| Morton | Scotland | Kirkcudbrightshire | Palnure | Kirkmabreck | - 1852 - | 12352 | 1180 | |
| Mowat | Scotland | Aberdeen | Fetteress | Stonehave | 1802 | 8686 | 646 | |
| Muldowney | Ireland | Kilkenny | Fassedin | Mothel | Corbetstown | 1794 + | 8686 | 759 |
| Murphy | Ireland | Knockbreda | Ballymacarrett | 1800 - | 6824 | 1159 | ||
| Nevin | Ireland | Down | Donaghade | Donaghade | C 1848 | 3487 | 724 | |
| Newton | Ireland | Limerick | 1818 - 1835 | 6503 | 877 | |||
| Nicolson | Scotland | Perthshire | Kinnoul | 1602 - 1786 | 3487 | 95 | ||
| Nicolson | Scotland | Perthshire | Perth | 1786 - 1851 | 3487 | 94 | ||
| Nimmo | Scotland | Ayr | Kirkoswald | -1756 | 5406 | 863 | ||
| Nimmo | Scotland | Ayrshire | Middbridg | pre 1811 | 5406 | 700 | ||
| Nolan | Ireland | Fermanagh | pre 1834 | 8049 | 752 | |||
| Nolan | Ireland | Kilkenny | Kilkenny | St Canice | Kilkenny | 1600 - 1800 | 2968 | 338 |
| Noonan | Ireland | Kings (Offally) | -1850 | 10713 | 1215 | |||
| Nowlan | Ireland | Kilkenny | Kilkenny | St Maul | Kilkenny | 1600 - 1800 | 2968 | 337 |
| Nugent | Ireland | Tipperary | Bansha / Kilmoyler | - 1850 - | 12352 | 1184 | ||
| O'Brien | Ireland | Fermanagh | pre 1843 | 8049 | 751 | |||
| O'Brien | Ireland | Clare | Killaloe | Ennis | Pre 1841 | 11445 | 1222 | |
| O'Connor | Ireland | Wexford | C 1775 | 3487 | 723 | |||
| O'Keeffe | Ireland | Clare | Ennis | Pre 1841 | 11445 | 1221 | ||
| O'Loughlin | Ireland | Clare | 1830 - 1850 | 12602 | 1254 | |||
| Orr | Scotland | Fife | Cults | 1790 - 1800 | 9165 | 1198 | ||
| Orr | Scotland | Fife | Kettle | 1780 - 1790 | 9165 | 1200 | ||
| Orr | Scotland | Fife | Ceres | 1750 - 1790 | 9165 | 1196 | ||
| O'Shea | Ireland | Kilkenny | Knockmajor | Damerstown | 1820 | 8686 | 816 | |
| O'Shea | Ireland | Kilkenny | Fassedin | Mohel | Corbetstown | - 1794 + | 8686 | 812 |
| O'Shea | Ireland | Kilkenny | Knockmajor | Corbetstown | 1820 | 8686 | 818 | |
| O'Sullivan | Ireland | Kerry | Castlemaine | 1800 - 1885 | 6058 | 1270 |