Rezső Kasztner, also known as Rudolf Israel Kastner, was a Hungarian-Israeli journalist and lawyer who became known for having helped a group of Jews escape from occupied Europe during the Holocaust on the Kastner train. After World War II, he was accused of having failed to informed the majority of Hungarian Jews about the reality of what awaited them in Auschwitz. He was assassinated in 1957 after an Israeli court accused him of having "sold his soul to the devil," a charge that was overturned by the Supreme Court of Israel in 1958.

The Kastner train is the name usually given to a rescue operation which saved the lives of over 1,600 Jews from Hungary during World War II. It consisted of 35 cattle wagons that left Budapest on 30 June 1944, during the German occupation of Hungary, ultimately arriving safely in Switzerland after a large ransom was paid to the Nazis. The train was named after Rudolf Kastner, a Hungarian-Jewish lawyer and journalist, who was a founding member of the Budapest Aid and Rescue Committee, a group that smuggled Jews out of occupied Europe during the Holocaust. Kastner negotiated with Adolf Eichmann, the German SS officer in charge of deporting Hungary's Jews to Auschwitz in German-occupied Poland, to allow over 1,600 Jews to escape in exchange for gold, diamonds, and cash. The deal was controversial and has been the subject of much debate and criticism, with some accusing Kastner of collaborating with the Nazis, while others argue that he made difficult choices to save lives.