John Charles Marshall, FRS is a British oceanographer and academic.
He is the Cecil and Ida Green Professor of Oceanography in the Department of Earth, Atmospheric and Planetary Sciences at the Massachusetts Institute of Technology (MIT).
Specific research interests include ocean convection and thermohaline circulation, ocean gyres and circumpolar currents, geophysical fluid dynamics, climate dynamics and numerical modeling of ocean and atmosphere.
He is the author or coauthor of over 150 refereed publications covering a wide range of topics in atmosphere, ocean and climate dynamics.
He is perhaps best known for his work on ocean convection, the dynamics of the southern ocean and as the architect of the MIT General Circulation Model (MITgcm), an open-source numerical model used by a broad community of researchers around the world.