Hilter? Stalin? Pol Pot? Obama (to be determined)?
Mugabe. He weaponized AIDS (OK, technically HIV, but lets not quibble.)
Like most Central African countries, a great deal of attention is given to a man's sex drive and potency in Zimbabwe as an indicator of his strength as a whole. You want to be the strongman in the country, you have to act the part, including banging many women.
How better to remove potential rivals than by infecting them with a horrible disease which makes them waste away before people's eyes.
Stalin used pneumonia successfully during the War. Soldiers with pneumonia would surrender to the Nazis, hoping to infect them.
My grandfather never talked about WW1, but he did mention shit flingers ('scuse language) once. In places where the trenches were pretty close together, some brave soul would use a slingshot to send the bowel movements of a cholera sufferer into the opposing trenches.
And, of course, we have Hamas. They have perfected the art of making seemingly innocent looking people go boom.