You didn't include Timur/Timurlenk/Tamerlane. He was as bad if not worse than Genhis Khan. Did almost exactly the same to the large cities in Asia as Genghis, except Samarkand was spared.
The murderous leader in numbers killed would probably Stalin. Not sure though. Since the 20th century leaders have killed far more people than others, I voted Genghis Khan. Trying to be different. Timur was equally bad. Their methods of killing were horrible.
Really Timur was worse than Genghis, because the Mongol was a barbarian, while Timur was educated and had appreciation for the arts and other things, yet he still murdered thousands. Sealed them in towers, build pyramids of skulls. When Ishfahan, a Persian city rebelled against him he ordered his soldiers to go into the city and return with 1 head. When he promised no blood shed, he found another way to kill his enemies, trampling them with horses, cementing them, etc.
What did Napoleon do? He had his secret police and all, but I don't think he killed people in the masses.
BTW, who is Vlad Tepes?