Grete Unrein (née Grete Abbe, 18 November 1872—5 November 1945) was a German politician from Jena active during the Weimar Republic, with a particular interest in social services. With her husband Otto Unrein she established the Jena Lyceum in 1912, now the Grete Unrein Comprehensive School (Integrierte Gesamtschule "Grete Unrein").