| William VIII | |
|---|---|
 | |
| Duke of Gascony | |
| Reign | 1052–1086 |
| Predecessor | Bernard II Tumapaler |
| Successor | William IX, Duke of Aquitaine |
| Duke of Aquitaine | |
| Reign | 1058–1086 |
| Predecessor | William VII, Duke of Aquitaine |
| Successor | William IX, Duke of Aquitaine |
| Born | Gui-Geoffroi c. 1025 Poitiers |
| Died | 25 September 1086 Chizé |
| Spouse | Garsende of Périgord Matoeda Hildegarde of Burgundy |
| Issue | Agnes of Aquitaine, Queen of León and Castile Agnes of Aquitaine, Queen of Aragon and Navarre William IX, Duke of Aquitaine |
| House | Ramnulfids |
| Father | William V, Duke of Aquitaine |
| Mother | Agnes of Burgundy |
William VIII (c. 1025 – 25 September 1086), born Guy-Geoffrey (Gui-Geoffroi), was duke of Gascony (1052–1086), and then duke of Aquitaine and count of Poitiers (as William VI) between 1058 and 1086, succeeding his brother William VII (Pierre-Guillaume).