| 301 | Margaret Tudor (28 November 1489-18 October 1541), parents: Henry VII and Elizabeth of York |
| 302 | Margareta of Holland (-after 12 August 1284) |
| 303 | Margred (-), parents: Dafydd Fychan ab Dafydd Llwyd |
| 304 | Marguerite de France (1157-shortly after 10 September 1197), parents: Louis VII "le Jeune/le Pieux" and Constanza de Castilla |
| 305 | Marguerite de France (around 1280-14 February 1318), parents: Philippe III "le Hardi" and Marie de Brabant |
| 306 | Marguerite III (1350-16 or 20 March 1405), Ctss of Flanders, Artois, Nevers and Rethel, Ctss Palatine of Burgundy, parents: Louis II “de Mâle” and Marguerite de Brabant |
| 307 | María de la Cerda (1319-13 March 1375), dame de Lunel |
| 308 | Marie de Blois (1136-1182), Ctss de Boulogne, parents: Stephen and Mathilde de Boulogne |
| 309 | Marie de Saint-Hilaire (-after 7 April 1399) |
| 310 | Mary Bohun (-), parents: John Bohun of Midhurst and Anne Arderne |
| 311 | Mary Grey (1545-20 April 1578), parents: Henry Grey and Frances Brandon |
| 312 | Mary of England (10 October 1344-1362 after 25 December), parents: Edward III and Philippa de Hainaut |
| 313 | Mary of England (12 March or 22 April 1279-before 8 July 1332), nun, parents: Edward I “Longshanks” and Leonor de Castilla |
| 314 | Mary of Lancaster (1320/21-1 September 1362), parents: Henry "Tortcol/Wryneck" of Lancaster and Maud Chaworth |
| 315 | Mary of York (11 August 1467-23 May 1482), parents: Edward IV and Elizabeth Wydeville |
| 316 | Mary Tudor (18 March 1496-June 1533), parents: Henry VII and Elizabeth of York |
| 317 | Mathilde de Blois (1133/34-before 1141), parents: Stephen and Mathilde de Boulogne |
| 318 | Mathilde de Boulogne (around 1104-1151), parents: Eustache III and Mary |
| 319 | Mathilde de Bretagne (around 1182/83 or 1185-before May 1189), parents: Geoffrey of England and Constance de Bretagne |
| 320 | Mathilde de Flandre (around 1032-2 November 1083), parents: Baudouin V “le Pieux/Insulanus” and Adela de France |
| 321 | Mathilde de Normandie (-26 April), parents: William I "the Conqueror" and Mathilde de Flandre |
| 322 | Matilda (-before 1202), Abbess of Barking, parents: Henry II |
| 323 | Matilda de Lancaster (1310-5 May 1377), canoness at the Augustine Abbey of Campsey, parents: Henry "Tortcol/Wryneck" of Lancaster and Maud Chaworth |
| 324 | Matilda of England (June 1156-28 June 1189), parents: Henry II and Eleonore d'Aquitaine |
| 325 | Maud Chaworth (2 February 1282-before 3 December 1322) |
| 326 | Maud Clifford (-26 August 1446), parents: Thomas de Clifford and Elizabeth de Ros |
| 327 | Maud of Lancaster (around 1340-10 April 1362), parents: Henry "of Grosmont" and Isabel Beaumont |
| 328 | Meurye (-), Lord of Gwent |
| 329 | Morfyoh (-), parents: Meurye |
| 330 | Morgan (around 1180/89-after 1213), Bishop of Durham, parents: Henry II and Nesta |