Mao zedong
Mao did not specifically target a group to be executed or persecuted, but did intend for peasants to focus more on steel production rather than crop production. When Mao initiated “The Great Leap Forward” he intended for peasants to stop what they were doing and work in steel factories as a way to increase the infrastructure. As a result famine spread throughout China affecting the poor the most. It is estimated that he killed 45 million people, the most of all time. To put that into perspective, the death toll of World War II was 55 million people. Mao Zedong qualifies as one of the worst mass murderers of all time.
http://i1.wp.com/8list.ph/wp-content/uploads/2013/07/The-8-Worst-Genocides-in-Recent-History-1v.jpg