SCP-049 is a humanoid entity in the garb of a medieval plague doctor who believes it is curing a "pestilence." The trouble is that its cure is death itself. Anyone its hand touches dies and, soon after, rises as a distorted corpse designated SCP-049-2 — while the doctor regards itself as devoted and speaks calmly and politely throughout.
The heart of the horror is madness wearing the mask of good intent. Death comes not from malice but from a twisted sense of mission, and the courteous bedside manner only sharpens the dread. Where the line between healing and killing collapses, it shows that the most terrifying figure is the one utterly convinced of its own righteousness.