Godfrey IV, known as the Hunchback, was a son of Godfrey the Bearded, whom he succeeded as Duke of Lower Lorraine in 1069, and Doda.
In the year of his succession, he married Margravine Matilda of Tuscany, daughter of his stepmother Beatrice of Bar, and thus became margrave of Tuscany. Godfrey and Matilda had only one child, Beatrice, who was born in 1071 and died the same year. From 1071 on, Godfrey lived apart from his wife. The two spouses were on opposite sides in the Investiture Controversy: Matilda was a partisan of Pope Gregory VII and Godfrey of Emperor Henry IV.
He warred on Henry's behalf against Magnus, Duke of Saxony, in 1075 and on that of the bishop of Utrecht in 1076 against Counts Dirk V of Holland and Robert I of Flanders. He was assassinated by spear in Vlaardingen while "answering the call of nature". Despite Matilda's opposition he nominated his nephew Godfrey of Bouillon to succeed him, but the emperor instead appointed his own son, Conrad. Godfrey of Bouillon succeeded eventually in 1087 and gained fame on the First Crusade.