Hartheim Castle near Linz, Austria, was one of National-Socialist Germany’s euthanasia centers. It entered the Holocaust stage with two affidavits containing claims attributed to Franz Ziereis, the former commandant of the Mauthausen Camp. Both affidavits are written by former Mauthausen inmates, one of them by Hans Maršálek. Both contain the claim that Ziereis allegedly confessed on his death bed to the murder of 1 to 1½ million people at Hartheim Castle. (See the entry on Hans Maršálek for more details.) Of course, no historian has ever taken that claim seriously. However, less excessive claims by other inmates or profile-neurotic historians can be found in the pertinent orthodox literature, claiming various figures of inmates from the Mauthausen camp complex to have been murdered/gassed at Hartheim Castle, and describing the location and design/setup of its alleged gas chamber in multifarious ways. (See Leuchter et al. 2017, pp. 168-171, for an overview.) Since none of the victims are claimed to have been Jews, no further elaboration is required here.