Hedwig Potthast was born in Cologne, the daughter of a businessman. After her final Abitur exams at secondary school, she trained as a secretary qualified in foreign languages. At the end of her training, she worked in Koblenz. Through Kurt Baron von Schröder, one of the founders of the Freundeskreis der Wirtschaft, she met Heinrich Himmler. From 1934 she was employed at the Gestapo headquarters in Berlin. Between early 1936 to early 1941, Potthast was Himmler's private secretary, and in this function was particularly responsible for Himmler's sponsorships and giving of awards.
They confessed to each other that they were in love at Christmas 1938. They thought about a "decent" way to be together, but it resulted only in an adulterous relationship from 1940 onwards. Himmler's wife, Margarete Himmler, with whom he had the daughter Gudrun, found out about Himmler's mistress at the latest by February 1941. She felt humiliated and bitter, and Hedwig's parents rejected the extramarital relationship. Potthast first took up residence in Grunewald, and from 1943 she lived in Brückentin, near the estate of Oswald Pohl, because she was a friend of his wife, Eleonore. Lina Heydrich and Gerda Bormann were also among her friends. Later she lived in Berchtesgaden.
Potthast had two children with Himmler: a son (Helge, born 15 February 1942 in Sanatorium of Hohenlychen) and a daughter (Nanette-Dorothea, born 20 July 1944 in Berchtesgaden). Little is known about the relationship between Himmler and Potthast. The couple probably saw each other only rarely, due to Himmler's activity as Reichsführer-SS and Chief of Police. Presumably, neither Potthast nor Himmler's wife were informed of Himmler's secret work. Potthast's relationship with Himmler ended during the Nazi era of secrecy, and they met for the last time in mid-March 1945, after which they shared daily telephone calls until 19 April 1945.
When the war ended, she was in Achensee, and after learning of the death of Himmler on the radio on 23 May 1945, she went into hiding, living temporarily with Eleonore Pohl in Rosenheim. In June/July 1945, she was arrested there by members of the U.S. Army and interrogated for several days in Munich. Margarete and Heinrich Himmler's daughter, Gudrun, did not learn of her half-siblings until after the war. When she tried to make contact with them, Potthast refused. Potthast lived in Theissendorf and kept in contact with the family of Himmler's older brother, Gebhard Ludwig Himmler, in Gmund am Tegernsee, as well as Himmler's former close confidant, Karl Wolff, until the 1950s. She re-married and took on her new husband's name. Her son struggled with ailments throughout life and stayed with her, and her daughter became a physician. In a 1987 interview with former Der Spiegel editor Peter-Ferdinand Koch, Potthast remained silent about Himmler's responsibility for Nazi war crimes. She died in 1997, in Baden-Baden.
- Himmler, Katrin (2007). The Himmler Brothers. London: Pan Macmillan. ISBN 978-0-330-44814-7.
- Longerich, Peter (2012). Heinrich Himmler: A Life. Oxford; New York: Oxford University Press. ISBN 978-0-19-959232-6.