Adelaide of Normandy (or Adeliza) (c. 1026 in Calvados, France - c. 1090) was the sister (or half-sister) of William the Conqueror.
She was the daughter of Robert the Magnificent, Duke of Normandy. Different chroniclers writing in the Gesta Normannorum Ducum call her sister of William the Conqueror either by the same mother or by different mothers. She is usually said to be daughter of Herleva.[1]
Adelaide married three times; first Enguerrand II of Ponthieu (died 1053) by whom she had issue; second Lambert II, Count of Lens (died 1054); and third in 1060 Odo II of Champagne son of the Count of Troyes, (Odo IV of Troyes), by whom she had issue Stephen, Count of Aumale. By Lambert she had a daughter, Judith of Lens, who married Waltheof, Earl of Northumbria (executed 1076). Their daughter, Maud, 2nd Countess of Huntingdon, took for her second husband King David I of Scotland.
She became Countess of Aumale when her husband Odo inherited the title of Count in 1069.