Carl Wilhelm Ramsauer (February 6, 1879 in Osternburg, Oldenburg – December 24, 1955 in Berlin) was an internationally notable professor of physics and research physicist, famous for the discovery of the Ramsauer–Townsend effect. He pioneered the field of electron and proton collisions with gas molecules.
From 1897 to 1907, Ramsauer studied at the Munich, Tübingen, Berlin, Kiel, London, and Breslau Universities. He was awarded his doctorate at Kiel.
From 1907 to 1909, Ramsauer was a teaching assistant to Philipp Lenard in the physics department at the Ruprecht Karl University of Heidelberg. It was here that he conducted research on the quantum effect of the transparency of noble gases to slow electrons, known as the Ramsauer–Townsend effect. Subsequently, he was a staff scientist at the Radiological Institute in Heidelberg. During World War I, he served as an artillery officer. From 1921, he was an ordinarius professor at the Danzig Technische Hochschule.
From 1928 to 1945 he was director of the research division of the Allgemeine Elektrizitäts-Gesellschaft (AEG), an electric combine with headquarters in Berlin and Frankfurt-am-Main. During the period 1931 to 1945, in addition to his position at AEG, he was honorary professor at the Berlin Technische Hochschule; the title meant that he was authorized to teach at the facility, but not required. From 1945, he was ordinarius professor and director of the physics department at the Berlin Technische Hochschule.