In ancient Roman religion and myth, Faunus [ˈfau̯nʊs] was the rustic god of the forest, plains and fields; when he made cattle fertile he was called Inuus. He came to be equated in literature with the Greek god Pan, after which Romans depicted him as a horned god.

Faunus was one of the oldest Roman deities, known as the di indigetes. According to the epic poet Virgil, he was a legendary king of the Latins. His shade was consulted as a goddess of prophecy under the name of Fatuus, with oracles in the sacred grove of Tibur, around the well Albunea, and on the Aventine Hill in ancient Rome itself.

Marcus Terentius Varro asserted that the oracular responses were given in Saturnian verse. Faunus revealed the future in dreams and voices that were communicated to those who came to sleep in his precincts, lying on the fleeces of sacrificed lambs. Fowler (1899) suggested that Faunus is identical with Favonius, one of the Roman wind gods (compare the Anemoi).