Maurice Kraitchik (April 21, 1882 - August 19, 1957) was a Belgian mathematician, author, and game designer. Born in Minsk, he was famous for having inspired the Two envelopes problem in 1953. He wrote several books about math and number theory. In 1910, he graduated from the University of Liege. In 1923, he graduated from the Université Libre de Bruxelles. During World War II, he traveled to the United States and taught at the New School for Social Research in New York City. He died in Brussels.