Gerhard Heinrich Dieke, (Rheda, Germany, 1901–Aberdeen, Scotland, August 26, 1965) was a German/U.S. physicist. He was a pioneer in investigating the structure of atoms and molecules by spectroscopic methods. Dieke studied at the University of Leiden under Paul Ehrenfest, and received a Ph.D. in physics at the University of California in 1926. After completing his graduate studies, he worked at the Institute of Physical and Chemical Research in Tokyo and in 1929 he was Dirk Coster's assistant at the University of Groningen in the Netherlands. Dieke joined the Department of Physics at Johns Hopkins University in 1930 as an associate professor, and he later served as chairman of the department, 1950-1965.