William IV de was born about 1071 in Sussex, England. William IV de's father was William III de Warenne and his mother was Gundred. He had a sister named Edith de. He was the older of the two children. He died on May 11th, 1138.
‌William IV de were married in a religious ceremony in 1118. He had a biological son and two biological daughters, named William V de, Ada de and Gundred de.