| Ligny | |
| Subdivision Type1: | Country |
| Subdivision Name1: | Belgium |
| Source1 Location: | Wagnelée |
| Mouth Location: | Mazy at a place called Falnuée |
| Mouth Coordinates: | 50.5048°N 4.6698°W |
| Progression: | Orneau → Sambre → Meuse → North Sea |
| River System: | Meuse |
The Ligny is a stream in Belgium, a tributary of the Orneau on the right bank. Its waters eventually join the Meuse via the Sambre.