Karl-Otto Saur (February 16, 1902 in Düsseldorf – July 28, 1966 in Pullach) was State Secretary in the Reich Ministry of Armaments and War Production in Germany during the Nazi era and de jure last defence minister of the Third Reich.
Saur was an engineer by profession. After graduation, he joined Thyssen AG, where he became the director of the August Thyssen-Hütte. He was a member of the NSDAP from 1931. He joined the National Socialist Guild of German Engineers and the Todt Organization where he rose to be the right-hand man to Fritz Todt.
Following Todt's death in a 1942 plane crash, Saur became official deputy to the new armaments minister Albert Speer. Saur was seen as particularly ruthless in the enforcement of military targets, was involved in all aspects of increasing production including orders that regulated the flow of slave labour towards the end of World War II. From March 1944, he managed the day-to-day operations of the Jägerstab (Fighter Staff), a task force established by Speer to drive increase in fighter aircraft production.
In his political testament, Adolf Hitler named Karl-Otto Saur as the new defence minister (Minister of Munitions (Rüstung)).:648 From May 1945 Saur was in American custody. In 1948 he became a witness for the prosecution at the Nuremberg Krupp trials - the Americans offered him immunity from prosecution for war crimes if he turned in state evidence, as they wanted a trial to demonstrate the collective guilt of German industry. For this he was viewed as a traitor by industry and was socially isolated. During denazification he was classified as "fellow traveller" and was released shortly afterwards.
Saur founded an engineering consultancy in 1949, and also started a small publishing house. The resulting company Saur Verlag only became economically successful from the beginning of the 1960s under his son Klaus Gerhard Saur.