Portions of Charles Guiteau’s brain. Guiteau assassinated US President Garfield in 1881.
Well, he shot Garfield, at the least. The shot that hit landed in one of Garfield’s lumbar vertebrae, but completely missed the spinal cord. Though he was hurting pretty bad, had the doctors just bandaged up the wound, kept it sterile (as was common practice just 10 years later), and not tried to extract the bullet, it’s very unlikely Garfield would have died from his wounds. Even for the day, the extreme “treatment” of Garfield’s wounds was seen as far more harmful than good, by both the medical community and eventually the general public.
As Guiteau opined to the judge at his trial: "The doctors are the ones who killed Garfield; I just shot him!"