Trịnh Xuân Thuận (born 1948) is a Vietnamese-American astrophysicist.
Thuận was born in Hanoi, Vietnam. He completed his B.S. at the California Institute of Technology, and his Ph.D. at Princeton University. He has taught astronomy at the University of Virginia since 1976, and is a Research Associate at the Institut d’Astrophysique de Paris. He was a founding member of the International Society for Science and Religion.
He was the recipient of UNESCO's Kalinga Prize in 2009 for his work in popularizing science.
Thuận's areas of interest are extragalactic astronomy and galaxy formation. His research has focused on the evolution of galaxies and the chemical composition of the universe, and on compact blue dwarf galaxies.