Stephen le Gros was the second son of Stephen of Aumale

Stephen of Aumale

Stephen of Aumale was Count of Aumale from 1082 to 1127.He was son of Eudes de Blois, Count of Troyes and Count of Meaux, and Adelaide of Normandy, countess of Aumale, and sister of William the Conqueror...

. He married his cousin, the eldest daughter of Roger de Mortimer, his mother's nephew. By her they had one son, William Crassus

William Crassus

William Crassus, or Le Gros , was the son of Stephen Le Gros. William was from an Anglo-Norman baronial family long established in central Normandy. He inherited Sodbury from his uncle, William le Gros, 1st Earl of Albemarle, primo-genitus...

 or 'le Gros'.

It was in all probability from this marriage that William Crassus

William Crassus

William Crassus, or Le Gros , was the son of Stephen Le Gros. William was from an Anglo-Norman baronial family long established in central Normandy. He inherited Sodbury from his uncle, William le Gros, 1st Earl of Albemarle, primo-genitus...

 (or le Gros), the kinsman and follower of the elder William Marshal, Earl of Pembroke, sprung.