Saul Perlmutter is an American astrophysicist and Professor of Physics at the University of California, Berkeley. He shared the 2011 Nobel Prize in Physics with Brian P. Schmidt and Adam Riess for discovering that the expansion of the universe is accelerating.

Perlmutter leads the international Supernova Cosmology Project at Lawrence Berkeley National Laboratory, where he holds the Franklin W. and Karen Weber Dabby Chair. He is a member of the National Academy of Sciences and the American Academy of Arts and Sciences.

Beyond cosmology, Perlmutter teaches scientific-style critical thinking through the Berkeley course Sense & Sensibility & Science, since adapted into a high school curriculum, Scientific Thinking for All: A Toolkit, developed with the Lawrence Hall of Science and Nobel Prize Outreach. He is co-author, with John Campbell and Robert MacCoun, of Third Millennium Thinking: Creating Sense in a World of Nonsense (Little, Brown Spark, 2024), drawn from the same course.