Son of Guillermo VIII. He/She was born in 1071 and died in 1127. It seized the County of Toulouse in the absence of Raimundo IV, but then returned to cede. He/She went to the crusade with a formidable army that the Turks destroyed completely. Back to his homeland, his disorderly conduct caused an excommunication. He/She returned to take over the County of Toulouse and again missed him as he/she went to provide assistance to Alfonso of Aragon against the Saracens.
Guillermo de Aquitania, as it is known in the history of world literature, is one of the oldest versificadores of the Provençal language and in the chronic is known as the good Troubadour.