Josef Kramer (10 November 1906 – 13 December 1945) was a Hauptsturmführer in the SS and the Commandant of Auschwitz-Birkenau (from 8 May 1944 to 25 November 1944) and Bergen Belsen (from December 1944 to its liberation on 15 April 1945) concentration camps. Dubbed the "Beast of Belsen" by camp inmates, he was a German Nazi war criminal, directly responsible for the deaths of thousands of people. He was detained by the British Army after the Second World War, convicted of war crimes, and hanged on the gallows in the prison at Hamelin by British executioner Albert Pierrepoint.

Josef Kramer, an only child, was born and raised in Munich in a middle-class family. His parents, Theodore and Maria Kramer, brought him up as a strict Roman Catholic. In 1915, the family moved from Munich to Augsburg, where Josef Kramer attended school. He began an apprenticeship as an electrician in 1920. From 1925 to 1933, except for working in a department store and as an accountant, he was mostly unemployed.

He joined the Nazi Party in 1931 and the SS in 1932. His SS training led him into work as a prison guard and, after the outbreak of war, as a concentration camp guard.

In 1934, Kramer was assigned as a guard at Dachau. His promotion was rapid, obtaining senior posts at Sachsenhausen and Mauthausen concentration camps. Kramer became assistant to Rudolf Höss, the Commandant at Auschwitz in 1940. He accompanied Höss to inspect Auschwitz as a possible site for a new synthetic oil and rubber plant, "a vital industry given Germany's shortage of oil.".

Kramer was named Commandant of Natzweiler-Struthof concentration camp in April 1941. Natzweiler-Struthof was the only concentration camp established by the Nazis on present-day French territory, though there were French-run transit camps, such as the one at Drancy. At the time, the area in Alsace-Lorraine in which it was established had been annexed by Nazi Germany.

As commandant at Natzweiler-Struthof, Kramer personally carried out the gassings of 80 Jewish men and women, part of a group of 87 selected at Auschwitz to become anatomical specimens in a proposed Jewish skull collection to be housed at the Anatomy Institute at the Reich University of Strasbourg under the direction of August Hirt.^{[citation needed]}

Ultimately, the 87 inmates were transported to Natzweiler-Struthof; 46 of these individuals were originally from Thessaloniki, Greece. The deaths of 86 of these inmates were, in the words of Hirt, "induced" in an improvised gassing facility at Natzweiler-Struthof, and their corpses, 57 men and 29 women, were sent to Strasbourg. One male victim was shot as he fought to keep from being gassed.

Kramer was promoted to the rank of Hauptsturmführer (Captain) in 1942 and, in May 1944, was transferred to become the Lagerführer (camp commander) in charge of operations at Auschwitz II-Birkenau, the main centre used to kill inmates within the Auschwitz concentration camp complex, from 8 May 1944 to 25 November 1944. He was brought to Auschwitz to manage the gassings of new transports in May 1944, according to the Prosecution Judge Advocate at the War Crimes tribunal that convicted him of being responsible for the deaths committed at Auschwitz. There were a number of witnesses who said that he took an active part in the selection parades in that, for instance, he loaded people into the trucks and beat them when they resisted. At Auschwitz, Kramer soon became known among his subordinates as a harsh taskmaster. One of the defendants at the Frankfurt Auschwitz Trial, Dr. Franz Lucas, testified that he tried to avoid assignments given to him by Kramer by pleading stomach and intestinal disorders. When Lucas saw that his name had been added to the list of selecting physicians for a large group of inmates transferred from Hungary, he objected strenuously. Kramer reacted sharply: "I know you are being investigated for favouring prisoners. I am now ordering you to go to the ramp, and if you fail to obey an order, I shall have you arrested on the spot."