I voted Hitler, but Stalin, Pol Pot, Mao, and Kim Jung Il all come close..I personally think Hitler tops Stalin alittle bit, because he targeted certian groups. If you hate everyone your a jerk, if you target particular groups your a jerk and a bully. Stalin possibly had more evil done in the long run then, had Hitler won the war EVERYONE who was a jew, slav, gypsy, black, or asian would be dead or slaves.
Pol Pot, could very well have been the worst, but he fortunatly didn't have alot to work with. He had a small, already pretty poor country, with a small population. He did manage to kill off so many in the country, it has left a perminent dent though..Mostly for entirley no reason.
Mao- He was a self centered jerk like most dictators, but what makes him abit diffrent, he I think he honostly wanted to help...The Great Leap Forward, and Cultural Revolution were awful ideas, and millions upon millions died, but they took alot of work on his part to organize and put together..A really bad person does not use huge sums of his country's money (and even some of his own) on the people...Alot ended up dead, but I think he did have some good intentions...Except for the ones he killed to maintian power...but so many dictators have done that.
Kim Jung Il- Any guy who makes a video called "the nutritional value of grass" just so he doesn't have to divert money from giant parades to himself is just sick.