John Stuart Foster FRS FRSC (May 30, 1890 – September 9, 1964) was a Canadian physicist.
[1][2][4] Born in Clarence, Nova Scotia, he completed his Ph.D. at Yale University with a dissertation on the first measurements of the Stark effect in Helium.
In 1924 he gained an appointment as assistant professor at McGill University in Montreal, where he taught physics.
During World War II he served as a liaison officer for the National Research Council, working at the MIT-run Radiation Laboratory on radar research and development.
His son, John Stuart Foster Jr., graduated from the University of California in 1948, then became director of the Lawrence Livermore National Laboratory, director of Defense Research and Engineering for the U.S. Defense Department, and Vice President of T.R.W., Inc.