The ManyRoads web site has published a list of the various known sources of information about the victims of National Socialism from 1938 through 1945. The resources include information and data on persons known to have been persecuted on political grounds or for religion, nationality, sexual orientation, physical or mental handicaps, and other reasons as well.
The sites include information on Sinti and Roma (Gypsies), intellectuals, homosexuals, Catholics, Jews, and political opponents.
Again, the list points to online sources of information. You can find the list at: http://www.many-roads.com/2017/12/27/victims-of-national-socialism.