| Douglas Weir | |
| Name Official: | Douglas Weir |
| Dam Crosses: | Vaal River |
| Res Name: | Douglas Weir Reservoir |
| Location: | Northern Cape, South Africa |
| Operator: | Department of Water Affairs and Forestry |
| Dam Length: | 1063 m |
| Dam Height: | 10 m |
| Opening: | 1977 |
| Res Capacity Total: | 16 700 000 m³ |
| Res Surface: | 799 ha |
| Coordinates: | -29.0669°N 23.8336°W |
Douglas Weir is a dam on the Vaal River, near Douglas, Northern Cape, South Africa. It was established in 1896 and raised in 1977.