Robert S. Mulliken (1896-1986) was an American physical chemist and winner of the 1966 Nobel Prize in Chemistry. He is best known for his work in developing the molecular orbital theory of molecular structure.
Mulliken was named to the Advisory Committee on Uranium Research at the National Academy of Sciences in 1941, which reviewed the status of fission research. He took leave from his teaching duties at the University of Chicago after the University's Metallurgical Laboratory was founded in 1942, and served as a research associate, Coordinator of Information, and Director of Editorial Work and Information at the Met Lab. He was a signer of the Szilard Petition.
After the war, Mulliken continued his research into valence theory and molecular structure, which earned him the nickname "Mr. Molecule."
He was awarded the Nobel Prize in Chemistry in 1966 "for his fundamental work concerning chemical bonds and the electronic structure of molecules by the molecular orbital method." He was the recipient of many other honors, including the Priestley Medal, the highest honor of the American Chemical Society.