| Guillaume de Montfort | |
| Seigneur of Montfort | |
| Predecessor: | New title |
| Successor: | Amaury I de Montfort |
| Spouse: | Albreda de Nogent |
| Issue: | Amaury I de Montfort |
| Noble Family: | House of Montfort |
| Father: | Amaury, Count of Valenciennes (possibly) |
| Birth Date: | before 990 |
| Death Date: | before 1053 |
Guillaume de Montfort, also known as Guillaume of Hainaut, was a French nobleman of the end of the 10th century, the first Lord of Montfort-l'Amaury.
He was succeeded as Lord of Montfort-l'Amaury by his son Amaury I de Montfort.
Guillaume is possibly the son[1] [2] of Amaury, Count of Valenciennes.