Who is Otto Horn from the nonfiction book, Into That Darkness: An Examination of Conscience?

Otto Horn is one of Franz Stangl's work colleagues during the time when he is urged to police the Euthanasia and Extermination Programmes. Horn is a nurse. He is interviewed by Gitta Sereny as a character witness for Franz Stangl. He is forced to work the Euthanasia and Extermination Camps as well.

Horn is copes well despite being forced to work at a human butcher shop. His consolation may be that he is not in charge; the extermination camps are not his own idea and he will leave them as soon as he can.