This list is leaning horror-comedy but I guess that’s what I think of when dark.
Cabin in the Woods is a meta joke horror movie while also being a horror movie.
Tucker and Dale vs Evil is a lighter comedy-horror about horror tropes and mistaken preconceptions.
John Dies at the End is a great book and an ok movie. Having read the book first I can’t say how much a non-book reader gets the movie, because it’s so weird, but it has a lot of existential dread at its core. Sort of if Lovecraft wanted to be funny and crass.
List from Google of things I liked that fall into this category: Everything, Everywhere, All at Once, Happy Death Day. Freaky. Swiss Army Man. I, Tonya. Jojo Rabbit. Little Miss Sunshine.
What We Do in the Shadows also works as a movie recommendation.
It definitely leans funny but it’s still about vampires.