Guillaume was the son of unknown parents. The date and place of his birth have not been found.
His wife was Andregoto de Gascogne. They were married, but the date and place have not been found. They had no known children.
| Attribute | Date | Description | Details | Source | Multimedia | Notes |
|---|---|---|---|---|---|---|
| Nobility Title | FROM 0846 TO 0848 | duc de Gascogne |