William de Ferrers, 4th Earl of Derby was born circa 1168 to William de Ferrers, 3rd Earl of Derby (-1190) and Sibylla de Braose (-1227) and died circa 1247 of unspecified causes. He married Agnes de Kevelioch (c1174-1247) .
Siblings
| Name | Birth | Death | Joined with |
| William de Ferrers, 4th Earl of Derby (c1168-c1247) | 1168 | 1247 | Agnes de Kevelioch (c1174-1247) |
| Robert de Ferrers (-1227) | 1169 England | 1227 England | Joan de Boclande (-c1227) |
| Millicent de Ferrers (c1171-c1190) | |||
| Agatha de Ferrers (c1175-?) | |||
| Petronella de Ferrers (c1191-aft1237) | 1191 | 1237 | Hervey de Stafford (-1237) |
Children
| Name | Birth | Death | Joined with |
| William de Ferrers, 5th Earl of Derby (c1193-1254) | 1193 | 28 March 1254 | Sibyl Marshall (1209-bef1238) Margaret de Quincy (c1218-bef1285) |
| Bertha de Ferrers (1218-1267) | 1218 Thetford, Norfolk, England, United Kingdom | 10 February 1267 England, United Kingdom | Thomas de Furnival (1200-1238) Ralph Bigod (c1215-1260) |
| Sibyl de Ferrers (1216-?) | |||
| Thomas de Ferrers | |||
| Hugh de Ferrers | |||
Footnotes (including sources)