For me for example its “Eat me - a natural and unnatural history of cannibalism” by Bill Schutt. Its an amazing book that covers cannibalism in animals and then the history of it in humans (cultural, survival & medicinal cannibalism).
I got a lot of “oh why would someone read something like that?” And “that not something fun to read about!” From relatives but my friends enjoyed the stuff that I could tell them about cannibalism!
Love me a good history of torture book. I’ve got a book called something like “How They Died and Where They’re Buried” which is just entirely about how celebrities died and, yeah, where they’re buried. It’s super interesting. They give really short biographies for each celebrity so I’ve ended up learning a lot about people I wouldn’t otherwise normally look up.