From the Wikipedia
Thomas Midgley, Jr. (May 18, 1889 – November 2, 1944), was an American mechanical engineer turned chemist. He developed both the tetra-ethyl lead (TEL) additive to gasoline and chlorofluorocarbons (CFCs), and held over a hundred patents. While lauded at the time for his discoveries, today his legacy is seen as far more mixed considering the serious negative environmental impacts of these innovations. One historian remarked that Midgley "had more impact on the atmosphere than any other single organism in Earth history."