Tankmar Horn (16 August 1924 – 16 March 2018) was a Finnish diplomat, economist, and businessman. Due to his father's position as army officer, Horn lived in different places in his youth. During the Second World War he studied in Berlin and Hungary. After the war end he completed his studies in economics and subsequently he started working for the Finnish Ministry of Foreign Affairs. Horn spent a couple of year long periods of secondment in a number of countries. He ended up negotiating trade agreements with EEC and he also took part in Nordek negotiations which eventually failed.