| Saint-Denis | |
| Settlement Type: | Sub-municipality of Mons |
| Image Map1: | Saint-Denis Mons Hainaut Belgium Map.svg |
| Map Caption1: | Location of Saint-Denis in Mons |
| Pushpin Map: | Belgium#Belgium Hainaut |
| Subdivision Type: | Country |
| Subdivision Type1: | Community |
| Subdivision Type2: | Region |
| Subdivision Type3: | Province |
| Subdivision Type4: | Arrondissement |
| Subdivision Name4: | Mons |
| Subdivision Type5: | Municipality |
| Subdivision Name5: | Mons |
| Coordinates: | 50.4919°N 4.0181°W |
| Population Density Km2: | auto |
| Postal Code Type: | Postal codes |
| Postal Code: | 7034 |
| Area Code Type: | Area codes |
| Area Code: | 065 |
Saint-Denis (pronounced as /fr/; Walloon: Sint-Dnis) is a sub-municipality of the city of Mons located in the province of Hainaut, Wallonia, Belgium. It was a separate municipality until 1964. In 1964, it was merged into Obourg. On 1 January 1972, Obourg was merged into Mons.[1]