| Father | Thomas Ap Guillem Herbert (1356 - 1438) |
| Mother | Maud de Morley (1369 - 1438) |
| Sibling | William ap Thomas (1394 - 1445) |
| Sibling | Mawd merch Thomas (1385 - ) |
| Sibling | Dydfil ap Thomas (1388 - ) |
| Sibling | Elizabeth merch Thomas (1390 - ) |
| Sibling | Hywel ap Thomas (1392 - 1446) |
| Sibling | Evan ap Thomas (1393 - ) |
| Sibling | Howel Guillen Herbert (1395 - ) |
| Sibling | Phillip Thomas (1396 - 1460) |
| Sibling | Dafydd ap Thomas (1397 - ) |
| Sibling | Philip ap Thomas of Llansantffraed (1399 - 1469) |
| Sibling | William Thomas Herbert (1401 - 1446) |
| Sibling | Alice ferch Jenkin (1410 - 1460) |