I think you should not get too far away from what people actually were, by trying to apply modern sensibilities for a single generalized category name. It gets a bit too muddy around the edges.
I like the idea of two categories: Nazis and Nazi Collaborators.
Very few Germans were Nazis. This was a political party. Membership was invitational and official, and membership in the party granted certain perks like good jobs and positions.
And then there were the Gestapo, which was an elite paramilitary force who were really the ones in charge of all aspects of the death camps. They were highly regarded for their efficiency in Germany because to justify their existence, they did not detract from the war effort, but financed the process of the camps entirely via the funds of their victims. It was a self-sustaining enterprise of victmization.
Then there were the SS, the secret police. The agendas of these various groups kept each of them a bit off balance, by design, so that Hitler could consolidate his power by playing one off against the other. All of these by definition were probably Nazis first.
Officers in the war may or may not have been Nazis. Or the party membership requirement may have changed over time, as skilled officers in the field of battle were necessary, but separate from the political operations. I'm not sure how restrictive it was to become a military officer. Perhaps the non-party members who were officers were the ones more likely to be transferred to the Russian Front. So politics does matter.
So then if a person was not a party member, but had a hand in the atrocities, I would categorize him as Nazi Collaborator.
For instance, I was just working on a profile of an esteemed writer of Vichy France. His name ended up on the black list compiled by the Resistance after the war. I think I would categorize him as a Vichy Collaborator, if such a category came about.
His later son-in-law was a Polish Jew, who became a Resistance Member during the war, and escaped several times.
