"Denier" is a term attached to anyone who questions any part of the established narrative. I'm also a Climate Denier, and a Science Denier, and a bunch of other kinds of "deniers."
As far as "The Holocaust" goes, there's a ton of seeming fabrication there, used for political motives, mostly as a lever to establish Israel. Good on 'em, it worked. However, I've visited a couple of the Concentration camps and read the sign plaques on the furnaces. I was super-surprised by the low number of victims, so I looked into the other camps, about 20 of them, same thing, some more than others, but no where near 1 million. If gassing was the most efficient way of killing then it should have accounted for a lot more. I read about where the 6 million number comes from, and it's derived from the census of how many Jews there were before the war vs. the census after the war. 6 million Jews lived in Germany in 1933; none afterwards (that would write it on a census anyway). Too coincidental. Just because I make this observation, in today's environment, that makes me a "denier."