Josef Mengele

Ishii was a microbiologist and the lieutenant general of Unit 731, a biological warfare unit of the Imperial Japanese Army during the Second Sino-Japanese War. He was born in the former Shibayama Village of Sanbu District in Chiba Prefecture, and studied medicine at Kyoto Imperial University. In 1932, he began his preliminary experiments in biological warfare as a secret project for the Japanese military. In 1936, Unit 731 was formed. Ishii built a huge compound — more than 150 buildings over six square kilometers — outside the city of Harbin, China.

Some of the numerous atrocities committed by Ishii and others under his command in Unit 731 include: vivisection of living people (including pregnant women who were impregnated by the doctors), prisoners had limbs amputated and reattached to other parts of their body, some prisoners had parts of their bodies frozen and thawed to study the resulting untreated gangrene. Humans were also used as living test cases for grenades and flame throwers. Prisoners were injected with inoculations of disease, disguised as vaccinations, to study their effects. To study the effects of untreated venereal diseases, male and female prisoners were deliberately infected with syphilis and gonorrhea via rape, then studied. A complete list of these horrors can be found here.

Having been granted immunity by the American Occupation Authorities at the end of the war, Ishii never spent any time in jail for his crimes and died at the age of 67 of throat cancer.

Granted he is a character of legend, but Daedalus deserves a place on any list of this type because he is probably the first recorded mad/evil scientist. Daedalus is often credited with inventing the very first labyrinth in which he imprisoned the step-son of King Minos, a minotaur. He is also, sadly, charged with killing his own son, though inadvertently, by creating Icarus and himself a set of wings used to escape his very own labyrinth. Icarus didn’t heed his father’s warnings about flying too close to the sun, thus melting his wings and plummeting to the earth.