Johann Radon (December 16, 1887–May 25, 1956) was a mathematician born in Litomerice in Bohemia (now Czech Republic). He wrote a doctoral dissertation on calculus of variations in 1910, at the University of Vienna.

He is best known now for:

• his part in the Radon-Nikodym theorem;
• the Radon measure concept of measure as linear functional;
• the Radon transform, in integral geometry, based on integration over hyperplanes — with application to tomography for scanners (see tomographic reconstruction).
• the Radon's theorem.