Thaumas ( ancient Greek Θαύμας ) is a sea god of Greek mythology. He is the son of Pontus and Gaia and the father of the Harpies Okeanostochter Elektra and the iris. After the late antique tradition Thaumas is also the father of the Indian River Hydaspes God.

The name Thaumas was brought in ancient times with the word θαῦμα "miracle" in conjunction. This interpretation is rejected by the research that compares Thaumas with the mythical namesake of the Thessalian city Thaumakos.