William de Ferrers Third Earl of Derby 300,748,1186
- Born: Abt 1136, Derbyshire, England 300,1186
- Christened: 1136, Castle, Tutbury, Staffordshire, England
- Marriage (1): Sibyl (Sibilla) de Braose Countess Derby
- Died: 21 Oct 1190, Acre, Palestine about age 54 300,1186,1187
- Buried: 21 Oct 1190, Jerusalem, Palestine 1187
Noted events in his life were:
• Lands. 300,748,1186 William was ousted of his dignities of Derby and Nottingham by King Richard I (Lionhearted) but they were soon after restored to him.
• Crusader, 1190, Acre, Palestine. 300,748,1186,1188 William accompanied Richard I on a crusade and lost his life during the siege of Acre.
William married Sibyl (Sibilla) de Braose Countess Derby, daughter of William II de Braose Third Lord Bramber and Bertha de Pitres of Gloucester. (Sibyl (Sibilla) de Braose Countess Derby was born about 1150 300,1189 and died in 1227 300,1189.)