John Adam Fleming, (January 28, 1877 – July 29, 1956) was an American geophysicist interested in the magnetosphere and the atmospheric electricity.

Fleming worked first at the United States Coast and Geodetic Survey with his superior Louis Agricola Bauer, who founded the Department of Terrestrial Magnetism at the Carnegie Institution of Washington.

In 1925, Fleming served as president of the Philosophical Society of Washington.

[2][3][4] He was one of the main organizers of the Washington Conferences on Theoretical Physics (1935–1947) with George Gamow.

[3] Since 1960 the American Geophysical Union rewards notable scientists in the field of research about the magnetosphere and atmospheric electricity.