| Lady Evelyn River | |
| Pushpin Map: | Canada Ontario |
| Pushpin Map Caption: | Location of the mouth of the Lady Evelyn River in Ontario |
| Subdivision Type1: | Country |
| Subdivision Name1: | Canada |
| Subdivision Type2: | Province |
| Subdivision Name2: | Ontario |
| Subdivision Type4: | Districts |
| Source Confluence: | North Lady Evelyn River and South Lady Evelyn River |
| Source Confluence Location: | Timiskaming, Unorganized, West Part |
| Source Confluence Coordinates: | 47.3472°N -80.4847°W |
| Source Confluence Elevation: | 360m (1,180feet) |
| Mouth: | Montreal River |
| Mouth Location: | Mowat Landing |
| Mouth Coordinates: | 47.4631°N -79.9878°W |
| Mouth Elevation: | 274m (899feet) |
The Lady Evelyn River is a river in Nipissing, Sudbury and Timiskaming Districts, Ontario, Canada.
The river begins at the confluence of the North and South Lady Evelyn Rivers and flows to its mouth at the Montreal River. It lies mostly in Lady Evelyn-Smoothwater Provincial Park, and mostly within Timiskaming District, with the exception of a short portion of the South Branch at its most southern stretch, which lies in northeastern Sudbury District, and of the southernmost tip of Lady Evelyn Lake, which lies in northwestern Nipissing District. Numerous waterfalls are found along the Lady Evelyn River, such as Frank's Falls. The most impressive and highest is Helen Falls where water cascades from a height more than 250NaN0.[1]