Adelaide of Normandy (or Adeliza) (c. 1030 - bef. 1090) was the sister of William the Conqueror and Countess of Aumale in her own right.
She was the daughter of Robert the Magnificent, Duke of Normandy and born c.1030 Elisabeth Van Houts, in her article Les femmes dans l’histoire du duché de Normandie (or Women in the history of ducal Normandy) mentions Countess Adelaide as one of those notable Norman women who were known to have exerted a stong influence on their chldren especially with regard to passing on their own family history.
Adelaide's first marriage to Enguerrand II, Count of Ponthieu potentially gave then Duke William a powerful ally in upper Normandy. But at the Council of Reims in 1049, when the marriage of Duke William with Matilda of Flanders was prohibited based on consanguinity, so were those of Eustace II, Count of Boulogne and Enguerrand of Ponthieu, who was already married to Adelaide. Adelaide's marriage was apparently annulled c.1049/50 and another marriage was arranged for her, this time to Lambert II, Count of Lens, younger son of Eustace I, Count of Boulogne forming a new marital alliance between Normandy and Boulogne.