Worst Criminals In History

[Madame Adequate]

I will presume, however, that you do not mean worst in the sense of most incompetent, but rather in terms of most evil/prolific.

Let me tell you; it's not some nutjob cannibal.

Harold Shipman gets my vote. A nice, middle-class doctor, very caring and kind, listening and supportive, loved his patients, frequently made house calls, killed 250 people deliberately and carefully, with morphine injections that he knew would never cure them...

Against, as deplorable as it is, he doesn't even come close. Serial killers are both evil and terrifying, but they are a very far cry from the worst criminals in Human history.