Guy II of Ponthieu ( -- 1147 ) , the son of William III of Ponthieu and Helie of Burgundy , succeeded his father as Count of Ponthieu during William 's lifetime .
Guy II of Ponthieu ( -- 25 December 1147 ) was the son of William III of Ponthieu and Helie of Burgundy . 
 He succeeded his father as Count of Ponthieu before 1129 ; this was during William 's lifetime .