Marc Kastner is Donner Professor of Physics Emeritus at MIT and adjunct professor of physics at Stanford University. He was the founding president of the Alliance in 2015 before transitioning to an external science advisor position in 2020. Prior to leading the Alliance, Kastner had a long career in a variety of senior positions at the Massachusetts Institute of Technology (MIT). Kastner joined MIT in 1973 and was named the Donner Professor of Physics in 1989. He became director of the Center for Materials Science and Engineering in 1993, head of the Department of Physics in 1998 and dean of the School of Science in 2007.

Kastner is the current chair of the Basic Energy Sciences Committee of the U.S. Department of Energy. He has served as chair of the Solid State Sciences Committee and as chair of the Board on Physics and Astronomy of the National Research Council. He has also served on the Science Advisory Boards of the National Cancer Institute and the Gordon and Betty Moore Foundation. Kastner is a member of the National Academy of Sciences, a fellow of the American Academy of Arts and Sciences, the American Physical Society, and the American Association for the Advancement of Science. In 1995, he received the David Adler Lectureship Award of the American Physical Society, and in 2000 he won the Oliver E. Buckley Prize of the American Physical Society. Kastner received a B.S. in chemistry, an M.S. in physics, and a Ph.D. in physics from the University of Chicago and was a postdoctoral fellow at Harvard University.