Fanatical regimes throughout history

[Lumpy]

For all that Hitler and the Nazis have been regarded as the epitome of evil, and the struggle against them near-apocalyptic, the fact remains that the Nazi party ruled Germany for twelve years. In the span of centuries and millennia, twelve years is a blink of the eye. Yet if the Nazis could be so infamous in their day, how many other fanatical, murderous, psychotic regimes have come and gone through the ages? I vaguely recall reading about various heresies in the Middle Ages that had cultlike followings for a few years, there was the Tai Ping rebellion in China, and much further back, a brief Chinese dynasty that was proto-totalitarian. Can anyone cite some good examples?