William X of Aquitaine

William X, Duke of Aquitaine
Saint Bernard of Clairvaux converts William of Aquitaine
Spouse(s)	Aenor de Châtellerault
Noble family	Poitiers
Father	William IX, Duke of Aquitaine
Mother	Philippa of Toulouse
Born	1099 Toulouse
Died	9 April 1137(1137-04-09) (aged 37–38)

William X (1099 – 9 April 1137), called the Saint, was Duke of Aquitaine, Duke of Gascony, and Count of Poitou (as William VIII) from 1126 to 1137. He was the son of William IX by his second wife, Philippa of Toulouse.

William was born in Toulouse during the brief period when his parents ruled the capital. His birth is recorded in the Chronicle of Saint-Maixent for the year 1099: Willelmo comiti natus est filius, equivoce Guillelmus vocatus ("a son was born to Count William, named William like himself"). Later that same year, much to Philippa's ire, Duke William IX mortgaged Toulouse to Philippa's cousin, Bertrand of Toulouse, and then left on Crusade.

Philippa and her infant son William X were left in Poitiers. When Duke William IX returned from his unsuccessful crusade, he took up with Dangerose, the wife of a vassal, and set aside his rightful wife, Philippa. This caused strain between father and son, until 1121 when William X married Aenor de Châtellerault, a daughter of his father's mistress Dangerose by her first husband, Aimery.

William had three children with Aenor:

He possibly had one natural son, William. For a long time it was thought that he had another natural son called Joscelin and some biographies still erroneously state this fact, but Joscelin has been shown to be the brother of Adeliza of Louvain. The attribution of Joscelin as a son of William X has been caused by a mistaken reading of the Pipe Rolls pertaining to the reign of Henry II, where 'brother of the queen' has been taken as Queen Eleanor, when the queen in question is actually Adeliza of Louvain. William, called of Poitiers in the Pipe rolls may have been a half brother of Eleanor. Chronicler John of Salisbury tells us that Petronilla died in 1151 or 1152, after which her husband Raoul of Vermandois briefly remarried.