Lester S. Hill (1891–1961) was an American mathematician and educator who was interested in applications of mathematics to communications. He received a bachelor's degree (1911) and a master's degree (1913) from Columbia College and a Ph.D. from Yale University (1926). He taught at the University of Montana, Princeton University, the University of Maine, Yale University, and Hunter College. Among his notable contributions was the Hill cipher. He also developed methods for detecting errors in telegraphed code numbers and wrote two books.