Shirō Ishii
Ishii led the creation and use of biological weapons at Unit 731 in Manchukuo during the Second Sino-Japanese War from 1937 to 1945, including the bubonic plague attacks at Chinese cities of Changde and Ningbo, and planned the Operation Cherry Blossoms at Night biological attack against the United States. Ishii and his coworkers also  experimented with humans unethically, resulting in the deaths of over 10,000 people, most of them civilians or prisoners of war. Ishii was later granted immunity in the International Military Tribunal for the Far East by the United States government in exchange for information and research for the U.S. biological warfare program.