Lee Smolin is an American theoretical physicist, a researcher at the Perimeter Institute for Theoretical Physics, and an adjunct professor of physics at the University of Waterloo.

Smolin is best known for devising several approaches to quantum gravity, in particular loop quantum gravity. He advocates that the two primary approaches to quantum gravity, loop quantum gravity and string theory, can be reconciled as different aspects of the same underlying theory. His research interests also include cosmology, elementary particle theory, quantum mechanics, and the philosophy of science and economics.

Smolin received his undergraduate degree at Hampshire College. He then went on to earn his PhD in theoretical physics from Harvard University. Smolin then earned postdoctoral degrees at the Institute for Advanced Study in Princeton, New Jersey, the Institute for Theoretical Physics at the University of California, Santa Barbara, and the University of Chicago.

Smolin held faculty positions at Yale, Syracuse and Penn State University. A Fellow of the American Physical Society and of the Royal Society of Canada, Smolin was awarded the 2009 Klopsteg Memorial Award from the American Association of Physics Teachers and in 2008 was voted 21st on a list of the 100 most influential public intellectuals by Prospect and Foreign Policy Magazines. He is also adjunct professor of physics at the University of Waterloo and a member of the graduate faculty of the philosophy department at the University of Toronto.