Sir J.J. Thomson, OM PRS, Nobel Prize in Physics 1906

Wikipedia Biographical Summary:

Sir Joseph John "J. J." Thomson, OM, FRS (18 December 1856 – 30 August 1940) was a British physicist and Nobel laureate. He is credited for the discovery of the electron and of isotopes, and the invention of the mass spectrometer. Thomson was awarded the 1906 Nobel Prize in Physics "in recognition of the great merits of his theoretical and experimental investigations on the conduction of electricity by gases".