Hermann Kastner (1886–1957) was a German politician and served as the deputy prime minister of East Germany between 1949 and 1950.

He defected and obtained political asylum from West Germany shortly before he died in Munich.

[1][3] He became a member of the German Democratic Party (DDP) in 1918 and began to work as a lawyer in Dresden from 1920.

[1] He was the minister of justice in the cabinets led first by Rudolf Friedrichs and then by Max Seydewitz between 14 December 1946 and 10 April 1948.

[3] The reason for his removal from both the post of deputy premiership and from the LDPD was the defection of his son to West Germany on 18 April 1950.

[3] He was named as the chairman of the Promotion Committee for Intelligence at the East German Council of Ministers with the rank of state secretary in 1951 which he held until 1955.

[8][9] Years later it was revealed that Kastner was the leading informer of the Gehlen Organization, an intelligence agency established by the USA following the end of World War II.