4. Cecilia (or Cecily) (c. 1056 – 1126), Abbess of Holy Trinity, Caen.

William Conqueror is known to have had nine children, though Agatha, a tenth daughter who died a virgin, appears in some sources. Several other unnamed daughters are also mentioned as being betrothed to notable figures of that time. Despite rumours to the contrary (such as claims that William Peverel was a bastard of William)[20] there is no evidence that he had any illegitimate children.

http://en.wikipedia.org/wiki/Cecilia_of_Normandy

-------------------- The book, 'Kings & Queens of Great Britain'