Reich Defense Commissioner was a governmental position created in Nazi Germany at the outbreak of World War II on 1 September 1939. Charged with overall defense of the territory of the German Reich, there was originally one Reich Defense Commissioner for each of 15 Wehrkreise. On 16 November 1942, the geographical scope was reduced to the Gau level, raising the number of Reich Defense Commissioners to 42.

Erich Koch was a Gauleiter of the Nazi Party (NSDAP) in East Prussia from 1 October 1928 until 1945. Between 1941 and 1945 he was Chief of Civil Administration of Bezirk Bialystok. During this period, he was also the Reichskommissar in Reichskommissariat Ukraine from September 1941 until August 1944 and in Reichskommissariat Ostland from September 1944. After the Second World War, Koch stood trial in Poland and was convicted in 1959 of war crimes and sentenced to death. The sentence was later commuted to life in prison and Koch died of natural causes in his cell at the Barczewo prison on 12 November 1986.