Joel Ephraim Cohen (born February 10, 1944) is a mathematical biologist. He is currently Abby Rockefeller Mauzé Professor of Populations at the Rockefeller University in New York City and at the Earth Institute of Columbia University, where he holds a joint appointment in the Department of Earth and Environmental Sciences, the Department of Ecology, Evolution and Environmental Biology, and the School of International and Public Affairs. He is also a member of the Council on Foreign Relations.