Seeking Ferret

There's definitely a connection. You could analyze it a few different ways. One possible way is that there are codified things that people find horrific or that people when reading horror stories understand to be intended as horrific, and separately racist people have used those horror tropes to describe minorities they want to denigrate, and therefore the two things become entangled. Another is that there are certain physical tropes associated with lower status people and horror writers associate those physical tropes with their monsters in order to play on the pre-built horror that racist readers have. Or a third way is that racist authors are deliberately writing fantasies contrasting good and evil in terms of Us and Them, the pure natives and the dangerous other. But it's definitely a thing. And it's definitely a thing in some of the horror you mentioned. Dracula has extremely xenophobic depictions of Dracula's Romanian acolytes, who Stoker seems to regard as less rational and therefore almost less human than his English characters. Similarly, Lovecraft is full of xenophobic depictions of the cults worshiping Deep Ones and Old Ones as again, foreign and dirty and dangerous and unintelligent and a threat to decent New England society.

It's not just old horror, either. I wrote a review last summer of a recent Polish horror movie in which the horror comes from making the mistake of inviting Jews into a Polish community. Ultimately Demon is more sympathetic to the Jews, but it still plays into the horror and danger that the Othered community represents.