They often form part of broader theories of Jewish conspiracies. According to defense attorney Kenneth Stern, "Historically, Jews have not fared well around conspiracy theories. Such ideas fuel anti-Semitism. The myths that all Jews are responsible for the death of Christ, or poisoned wells, or killed Christian children to bake matzos, or "made up" the Holocaust, or plot to control the world, do not succeed each other; rather, the list of anti-Semitic canards gets longer."
Some antisemitic canards date back to the birth of Christianity, while other conspiracy theories are more recent. Since at least the Middle Ages, antisemitism has featured elements of conspiracy theory. In medieval Europe it was widely believed that Jews poisoned wells, had been responsible for the death of Jesus, and ritually consumed the blood of Christians. The second half of the 19th century saw the emergence of notions that Jews and/or Freemasons were plotting to establish control over the world. Forged evidence has been presented to spread the notion that Jews were responsible for the propagation of Communism, the most notorious example being The Protocols of the Elders of Zion (1903). Such antisemitic conspiracy theories became central to the worldview of Adolf Hitler. Antisemitic theories persist today in notions concerning banking, Hollywood, the news media and a purported Zionist Occupation Government.