| Big Grassy River 35G | |
| Official Name: | Big Grassy River Indian Reserve No. 35G |
| Settlement Type: | Indian reserve |
| Pushpin Map: | Canada Ontario |
| Pushpin Mapsize: | 200 |
| Coordinates: | 49.0667°N -113°W |
| Subdivision Type: | Country |
| Subdivision Type1: | Province |
| Subdivision Type2: | District |
| Subdivision Name2: | Rainy River |
| Subdivision Type3: | First Nation |
| Subdivision Name3: | Big Grassy |
| Area Land Km2: | 33.73 |
| Population Footnotes: | [1] |
| Population Total: | 251 |
| Population As Of: | 2021 |
| Population Density Km2: | 7.4 |
Big Grassy River 35G is a First Nations reserve on the eastern shore of Lake of the Woods in Ontario, Canada. It is one of six parcels of land reserved for the Big Grassy First Nation.