Johannes Jahn (29 August 1885 – 10 July 1960) was a German trade unionist, politician and anti-Nazi activist. Jahn became a smelter, and then in 1909 began working for a trade union. By 1930, he was serving on the national executive of the United Union of German Railway Workers, and was an outspoken opponent of the Nazis. He opposed the dissolution of the unions in 1933, and managed to salvage a list of former union members in the Ruhr. This enabled him to set up a labour resistance group in the area, working closely with the International Transport Workers' Federation (ITF).