Karl Maier (1901 – 25 July 2000) was a German Esperantist and member of the Universala Esperanto Asocio, for more than 50 years. Maier learned Esperanto in 1924. After emigration from Germany in 1930, he was living with Esperanto enthusiasts among United States, Mexico and Japan. Between 1935 and 1955 he lived in China. After his return to Germany, he managed to unite several esperantists, reaching over 300 subscribers for the Chinese magazin El Popola Ĉinio (The Chinese People); promoted the regular Esperanto conventions in East Berlin (beginning in 1960) and fought for the legalization of the Esperanto language in the GDR.