Helmut Himpel (born 14 September 1907 in Schönau im Schwarzwald; died 13 May 1943 in Plötzensee Prison) was a German dentist and resistance fighter against Nazism. He was a member of the anti-fascist resistance group that was later called the Red Orchestra by the Abwehr. Himpel along with his fiancé Maria Terwiel were notable for distributing leaflets and pamphlets for the group. Specifically this included the July and August 1941 sermons of Clemens August Graf von Galen. The 2nd leaflet the couple posted, on Aktion T4 denouncing the murders of the sick by euthanasia, induced Hitler to stop the euthanasia murders and find other ways to do it.