Michael S. Turner (born July 29, 1949) is an American theoretical cosmologist who coined the term dark energy in 1998. He is the Rauner Distinguished Service Professor Emeritus of Physics at the University of Chicago, having previously served as the Bruce V. & Diana M. Rauner Distinguished Service Professor, and as the assistant director for Mathematical and Physical Sciences for the US National Science Foundation.

Turner's book The Early Universe, co-written with fellow Chicago cosmologist Edward Kolb, is a standard text on the subject. The 2003 National Academy study, Connecting quarks with the cosmos: eleven science questions for the new century, which Turner chaired, identified opportunities at the intersection of astronomy and physics and has helped shape science investment in the US in this area. In 2022, Turner was appointed as a co-leader, with Maria Spiropulu, of a National Academies of Science, Engineering and Medicine study, leading a committee of 17 physicists world-wide to consider the strategic vision of research in elementary particle physics.