In J. R. R. Tolkien's fictional universe of Middle-earth, the Carnen — Sindarin for Redwater — is a river that flows southward from the Iron Hills east of the Lonely Mountain until it meets the Celduin about 250 Númenórean miles to the south. From there the rivers flow as one to the Sea of Rhûn, past the land of Dorwinion.

It is not exactly clear what the name of the river is past the point where Celduin and Carnen meet, but the map suggests that Carnen becomes the name of the combined river. Although the area was not mapped by Tolkien the Carnen must have flowed past many villages of Men, as the Men of Dale and Esgaroth traded with someone in the region.