VicunaBlue said:
I have to say Mao Tse Tung.
We have a winner.
He was, after all, responsible for the world's biggest ever genocide. You guys think Hitler was bad? Or maybe you happen to know that Stalin was worse than him? But Mao was behind the deaths of 49,000,000-78,000,000 people. His MINIMUM death count was more than Hitler and Stalin combined.
Though, keep in mind that his count (as well as Stalin's, just so you know) includes negligence and indirect damage done by bad decision-making, I got that figure from here: http://www.scaruffi.com/politics/dictat.html .
A more conservative estimate is 40,000,000, found here: http://www.religioustolerance.org/genocide4.htm but it's still greater the second and third worst genocides in history put together (which would make 35,000,000 people put together).
In terms of pure numbers, there's no argument to be had, here. They're all terrible, but Mao is the worst. Not least because modern Chinese citizens are still brought up to love him.