Oscar Kempthorne (January 31, 1919 – November 15, 2000) was a British statistician and geneticist known for his research on randomization-analysis and the design of experiments, which had wide influence on research in agriculture, genetics, and other areas of science. Born in St Tudy, Cornwall and educated in England, Kempthorne moved to the United States, where he was for many decades a professor of statistics at Iowa State University.