William VI of Aquitaine (1004-1038), nicknamed the Fat, was Duke of Aquitaine and Count of Poitiers as William IV of Poitou between 1030 and 1038. William was the eldest son of William V of Aquitaine by his first wife Almodis of Gevaudun. William married Eustachie of Montreuil but had no known descendents.

See also: Dukes of Aquitaine family tree

Preceded by: William V	Duke of Aquitaine	Succeeded by: Otto
	Count of Poitiers