Leon Mestel (born 5 August 1927) is a British astronomer and astrophysicist and Emeritus Professor at the University of Sussex. His research interests are in the areas of star formation and structure, especially stellar magnetism and astrophysical magnetohydrodynamics. He has been awarded both the Eddington Medal (1993) and the Gold Medal of the Royal Astronomical Society (for Astronomy, 2002).