| Roaring Lion River | |
| Pushpin Map: | New Zealand#New Zealand South Island |
| Pushpin Map Size: | 270px |
| Pushpin Map Caption: | Mouth of the Roaring Lion River |
| Source1: | Tasman Mountains |
| Source1 Coordinates: | -41.0539°N 172.353°W |
| Mouth Location: | Karamea River |
| Mouth Coordinates: | -41.202°N 172.4298°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | New Zealand |
| Length: | 24km (15miles) |
| Progression: | Roaring Lion River → Karamea River → Ōtūmahana Estuary → Karamea Bight → Tasman Sea |
| Tributaries Left: | Breakfast Creek, Cub Stream |
| Tributaries Right: | Discovery Creek, Downey Creek, Cavern Creek, Grace Creek, Beautiful River |
The Roaring Lion River is a river in the Buller District of New Zealand's South Island located in Kahurangi National Park. It flows southeast from its source in the Tasman Mountains to the east of Mount Domett, gradually turning southwest before reaching the Karamea River east of Karamea.