David Guest (1911–1938) was a Communist British mathematician and philosopher who volunteered to fight in the Spanish Civil War and was killed in Spain in 1938. He had entered Trinity College, Cambridge, in 1929 and studied from 1930 to 1931 in Göttingen in Germany, where he became involved in anti-Nazi politics, and joined the Communist Party at Cambridge 1931. After leaving Cambridge he lectured in mathematics and worked for the Communist party, even teaching in a secondary school for English-speaking children in Moscow. In 1938 he left work as a lecturer at University College in Southampton to volunteer for the International Brigade fighting in Spain. He wrote of his decision:
After his death, notes he had made while lecturing at the Marx Memorial Workers' School were published as A Text Book of Dialectical Materialism in 1939.