| Ninian | |
| Pushpin Map: | France#France Bretagne |
| Mouth Coordinates: | 47.888°N -2.4365°W |
| Subdivision Type1: | Country |
| Length: | 60km (40miles) |
| Source1 Elevation: | 270m (890feet) |
| Mouth Elevation: | 25m (82feet) |
| Basin Size: | 306km2 |
The Ninian (in French pronounced as /ninjɑ̃/) is a river in Brittany, France. Its length is 59.6km (37miles). Its main tributaries are the Trelan (at Mohon), the Léverin (at Taupont), the Yvel (at Ploërmel) and the Guerfo. It flows into the Oust near to Montertelot.