Mao Zedong
From dKosopedia
Mao Zedong was an assistant librarian at Beijing University who went to become the foremost Chinese Communist military and political leader of the Twentieth Century. He led the Communist Party of China (CPC) to victory against the Kuomintang (KMT) in the 1945-1949 Chinese Civil War and to establish the People’s Republic of China (PRC) in 1949 dying in 1976.
An unknown number of Chinese, estimated to be tens of millions, died during the violence of the 1945-1949 Chinese Civil War the post-civil war land reforms. Tens of millions more are estimated to have perished in the famine caused by the 1957-1960 Great Leap Forward. A much smaller number also died during the chaos of the 1966-1969 Great Proletarian Cultural Revolution, which caused immense suffering and resulting in the immense loss of Chinese antiquities.
Zedong's "leap" caused the greatest number of human deaths on record for any singular event.