Margaret Mortimer was born on an unknown date to Roger Mortimer, 1st Baron Mortimer of Wigmore (1231-1282) and Maud de Braose (1224-1300) and died 1297 of unspecified causes. She married Robert de Vere, 6th Earl of Oxford (1257-1331) .
Children
| Name | Birth | Death | Joined with |
| Thomas de Vere (-bef1331) | |||