Geheimrat Leopold Koppel (20 October 1843 in Dresden – 29 August 1933 in Berlin) was a German banker and entrepreneur. He founded the private banking house Koppel und Co., the industrial firms Auergesellschaft and OSRAM, and the philanthropic foundation the Koppel-Stiftung. He was a Senator in the Kaiser-Wilhelm-Gesellschaft. An endowment he made in 1911 resulted in the founding of the Kaiser-Wilhelm Institut für physikalische Chemie und Elektrochemie, and endowments from him led to the founding of and support of the Kaiser-Wilhelm Institut für Physik. As a Jew, he was a target of the Third Reich’s policy of Arisierung – the Aryanization of German businesses, which began in 1933.