Eustace IV, Count of Boulogne (b. 1130)
Eustace IV (c. 1129/1131 – 17 August 1153) ruled the County of Boulogne from 1146 until his death. He was the eldest son of King Stephen of England and Countess Matilda I of Boulogne. When his father seized the English throne on Henry I's death in 1135, he became heir apparent to the English throne but predeceased his father.