Agnes of Aquitaine was a daughter of William VIII, Duke of Aquitaine and his third wife Hildegarde of Burgundy, and thus half-sister of Agnes of Aquitaine, Queen of Castile, with whom she is sometimes confused.

In 1081, Agnes was betrothed to Peter I of Aragon and Navarre

Peter I of Aragon and Navarre

Peter I was the King of Aragon and Navarre for a decade from 1094 until his death. He was the son and successor of Sancho V Ramírez by his first wife, Isabella of Urgell. He was named in honour of Saint Peter, because of his father's special devotion to the Holy See, to which he had made his...

. During 1086 in Jaca

Jaca

Jaca is a city of northeastern Spain near the border with France, in the midst of the Pyrenees in the province of Huesca...

 the couple married, and upon Peter's succession, Agnes became queen consort of Aragon

Aragon

Aragon is a modern autonomous community in Spain, coextensive with the medieval Kingdom of Aragon. Located in northeastern Spain, the Aragonese autonomous community comprises three provinces : Huesca, Zaragoza, and Teruel. Its capital is Zaragoza...

 and Navarre

Navarre

Navarre , officially the Chartered Community of Navarre is an autonomous community in northern Spain, bordering the Basque Country, La Rioja, and Aragon in Spain and Aquitaine in France...

. By him, Agnes had two children, both of whom predeceased their father:

• Peter of Aragon (died 1103)
• Isabella of Aragon (died 1104)

Agnes died in 1097, and her husband remarried to a woman named Bertha

Bertha of Aragon

Bertha of Aragon was a Queen consort of Aragon and Navarre. Nothing is known about her childhood or the names of her parents, it is believed that she is Italian since her name was Berta, which is Italian....

.