Eighty years ago the greatest mass murder of human beings of all time occurred in Nazi occupied Europe. This began with the mass extermination of patients with neurologic and psychiatric disorders that rendered them “useless eaters” to Hitler’s regime. The neuropsychiatric profession was systematically “cleansed” beginning in 1933, but racism and eugenics had infiltrated the specialty in the decades before that. With the installation of Nazi-principled neuroscientists, mass forced sterilization was enacted, which slowed down by the start of World War II and the advent of patient murder. But the murder of roughly 275,000 patients by the end of the war was not enough. The patients’ brains and neurologic body parts were stored and used in scientific publications both during and long after the war. Also, patients themselves were used in unethical ways for epilepsy and multiple sclerosis experiments. Relatively few neuroscientists resisted the Nazis, with some success in the occupied countries. Most neuroscientists involved in unethical actions continued their careers unscathed after the war. Few answered for their actions in a professional or criminal sense, and few repented. The legacy of such a depraved era in the history of neuroscience and medical ethics is that codes exist by which patients and research subjects are protected from harm. But this protection is possibly subject to political extremes and only by understanding the horrible past can our profession police itself. Individual neuroscientists can protect patients and colleagues if they are aware of the dangers of a utilitarian, unethical, and uncompassionate mindset.