It could be argued that these three could be held as the architects. As they laid down the framework.In 1904, Alfred Ploetz founded the German Eugenics Society. Sixteen years later, a work seminal to the development of the German eugenics movement, The Permission to Destroy Life Unworthy of Life, was published. Written by Karl Binding, a widely respected judge, and renowned psychiatrist Alfred Hoche, the work was key to the formulation of Nazi ideology, rhetoric and practice:
[It] defended the theory which stated that the elimination of "worthless people" should be legalized. Thus the concepts of "worthless life" or "life unworthy of life" used by the Nazis come from that book. Binding and Hoche speak in that book about "worthless human beings". [Binding and Hoche] plead for "the elimination of those who cannot be saved, ... whose death is an urgent need" ... [and] about those who are below the beast[s] [with] "neither the will to live nor to die". [The book also refers] to those who are "mentally dead" and who form "a foreign body to the human society".[5]
The industrialisation was developed by the Nazis. One could argue that Eichmann was the chief architect. But before the Wansee conference and the subsequent operation Reinhardt (1942), where he put forward the 'final solution', the extermination of 'undesirable' groups was already well under way. Eichmann simply proposed a more efficient system. Himmler made the inclusion of women and children mandatory as " - in other words, to kill them or have them killed—and to let the avengers in the form of the children grow up for our sons and grandsons to deal with. The difficult decision had to be taken to make these people disappear from the earth." Chilling stuff. The guy was talking about eradicating a race for no other reason than that eradication itself.
When all the groups targeted by the Nazis are taken into account the actual death toll rises to 9 - 11 million.
I suppose that yamangman is arguing that the British invented concentration camps in the Boer war. This is true. Though they existed before that in the form of Indian reservations in the United states. However the concept of the British concentration camps was to deny support to the Boer fighters not to exterminate the population. The fact that they were badly run and poor hygene led to a high death toll was not down to premeditation. More down to ignorance and appalling admin. Incidently the camps sorted their act out but political pressure at home closed them down. Which turned out to be a less than stellar success as the Boer families went back out on to the Veld where there was nothing for them and began to starve all over again. The reservations probably had more to do with economics than anything else. Which would explain why the Souix were moved from the Black hills when gold was discovered there.