thumb|right|[[Ernst Heinkel (right) with Siegfried Günter.]]
Siegfried Günter (8 December 1899 – 20 June 1969) and Walter Günter (8 December 1899 – 21 September 1937) were German twin brothers and pioneering aircraft designers. Walter was responsible for the world's first rocket-powered and turbojet airframes, projects funded by Nazi Germany. Siegfried was the father of the "thrust modulation theory". Avid flight enthusiasts, at 16 they had developed their own propeller theories. There they were to design some of the most important and famous designs associated with the company, including the Heinkel He 51, He 70, He 112, He 100, and the He 111. Walter designed the first ever retractable landing gear in Germany for the He 70, an aircraft mainly designed by Siegfried.
As chief project designer by 1937, Siegfried and his team introduced the He 100D-1 on 25 May 1937.
Siegfried would later contribute to the design of the He 219, as well as other prototypes, including the He 177 and He 162.
Death of Walter
Walter was killed in a car accident on 21 September 1937. In 1948 he was taken to the Soviet Union by USSR agents where he worked on Soviet aircraft designs.
East Germany
In July 1954 Siegfried returned to East Germany.