I'm not into dehumanization outside of porn. Inside porn, though, I like things like, collars and leashes, people in cages, and owners basically taking what they want regardless of whether or not the sex slave likes it or cares for it. I prefer "gratuitous" because when it's just so obviously and blatantly sexual enslavement for the purpose of titillation, then it becomes so unrelated to real life consent issues that it's easier to just distance myself from said consent issues of real life and enjoy the fantasy for what it is.

One of my recent favorites in that line has been the Mirrorverse Avengers series. I wish there was more like it.