Eustace IV (c. 1129 – 17 August 1153), Count of Boulogne, 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. At a council held in London on 6 April 1152, Stephen induced a small number of barons to pay homage to Eustace as their future king; but the Archbishop of Canterbury, Theobald of Bec, and the other bishops declined to perform the coronation ceremony on the grounds that the Roman curia had declared against the claim of Eustace.