William Fiennes 2nd Baron Saye and Sele  25
- Born: Abt 1442, Broughton Castle, Oxfordshire, England
- Marriage: Margaret Wykeham  about 1451 in Broughton Castle, Oxfordshire, England
- Died: 14 Apr 1471 about age 29
Cause of his death was Killed at the Battle of Barnet.
Constable of Porchester Castle and of Pevensey Castle for life, Vice Admiral to the Earl of Warwick, then High Admiral of England. He accompanied Edward IV on his flight into Flanders and his triumphal return to England at Ravenspur. The marriage of the second baron accounts for the rise of this branch of the family. He married Margaret Wykeham (died shortly before 30 May 1477), daughter and heiress of William Wykeham, otherwise Parrott, of Broughton Castle, Oxford. Her father was son and heir of Sir Thomas Wykeham, otherwise Parrott, third and only son to leave issue of William Parrott of Ash, near Overton, Hants, by Alice Champneys, daughter and heiress of William Champneys by Agnes, sister of William of Wykeham (1324\endash 1404), Bishop of Winchester from 1367 until death. By this marriage the Fiennes family acquired Broughton Castle which remains in 2000 the seat of the Lords Saye and Sele. For the next five generations, a thin line of only sons inherited Broughton Castle, but they did not assume the title and were never called to Parliament. The title was dormant, meaning that the rightful claimants never asserted their title.
William married Margaret Wykeham  [MRIN: 551611186], daughter of William Wykeham  and Joan Trumpington , about 1451 in Broughton Castle, Oxfordshire, England. (Margaret Wykeham  died in 1477.)