Gustav Siegfried Eins was a British black propaganda radio station during World War II operated by the Political Warfare Executive. It was the brainchild of Sefton Delmer, and claimed to be an illegal radio station operating within Nazi Germany. The callsign was based on the German Army phonetic alphabet for the letters GS, but had no meaning.

The broadcaster was Peter Seckelmann, a defector from Berlin, who used the name 'Der Chef' and claimed to be a fanatical Nazi. In the first Gustav Siegfried Eins broadcast, immediately after the flight of Rudolf Hess to Scotland, Der Chef ranted that "As soon as there is a crisis, Hess packs himself a white flag and flies off to throw himself and us on the mercy of that flat-footed bastard of a drunken old cigar-smoking Jew, Churchill!"

Most of Der Chef's diatribes were directed against low- and middle-ranking Nazi Party officials, which he portrayed as selfish,corrupt and sexually depraved gangsters whose behaviour shamefully contrasted with 'the devotion to duty shown by our brave troops freezing to death in Russia'.

The station operated until 1943, when the station was closed. The scripting ostensibly had the Gestapo storm the station and shoot Der Chef. Unfortunately, the recording engineer who played the transcription did not understand German, and played the "death" of Der Chef twice.

The station was replaced by Soldatensender Calais.