Biography
Sibyl Marshall was born 1209 to William Marshal, 1st Earl of Pembroke (1146-1219) and Isabel de Clare, 4th Countess of Pembroke (1172-1220) and died before 1238 of unspecified causes. She married William de Ferrers, 5th Earl of Derby (c1193-1254) 14 May 1219 JL .
Children
| Name | Birth | Death | Joined with |
| Agnes de Ferrers (?-1290) | 1290 | William de Vesci (?-c1253) | |
| Isabel de Ferrers (-c1260) | |||
| Maud de Ferrers (-1298) | England | 12 March 1298 England | William de Vivonne (-1259) |
| Sibyl de Ferrers | |||
| Joan de Ferrers (-1267) | |||
| Agatha de Ferrers (-1306) | |||
| Eleanor de Ferrers (-1274) | 1274 | Roger de Quincy (c1195-1264) | |
Footnotes (including sources)
| ‡ General |
| ¶ Death |
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