Carl Friedrich Freiherr von Weizsäcker (28 June 1912 – 28 April 2007) was a German physicist and philosopher. He was the longest-living member of the research team which performed nuclear research in Germany during World War II, under Werner Heisenberg's leadership. There is ongoing debate as to whether he, and the other members of the team, actually willingly pursued the development of an atomic bomb for Germany during this time.
Von Weizsäcker was one of several scientists taken into custody by the Allied Forces at the end of 1945.
Nonetheless, Weizsäcker and his fellows were held in the underground Alpine Redoubt until 1947. When American forces arrived, Heydrich escaped, and ordered Weizsäcker and several other scientists killed.