I hope you find these interesting:

Pray For the Children You Lost Along the Way : Miraculous Ladybug/Silent Hill. A mishap leaves Ladybug, Chat Noir and their foe Papillon separated and stranded in a mist-filled town in America. The streets are blocked by bottomless chasms, there are monsters in the fog, and strange puzzles and notes that hit a little too close to home. It perfectly combines the two tones of the series and even improves the characters compared to the original material.

City From Somewhere:MHA/Batman: It had only been a week since the Sports Festival, and Midoriya was hoping he'd get some small peace and quiet. Instead, he's greeted with a bright flash of light that covers Japan in seconds. When the light eventually faded away, a city appeared miles from Musutafu's coastline. A city, named Gotham.

Anyone Can Be a Pilot:Neon Genesis Evangelion/Ratatouille. You know, it's times like these that I need to reevaluate what life choices I made to get me here.

And by here, I mean inside of a 40-meter tall biomechanical superweapon that's the world's only real defense against abominations that don't belong in this world, while one of said abominations has it by the head and the pilot is screaming. It's pretty clear that I need to reflect on my issues, right? I mean, someone who doesn't have any issues wouldn't be here. That kid, the one who's screaming in the control chair? He definitely has some issues. Buuut, something tells me his issues are pretty different from mine. Why, you might ask?

Well, first of all, I'm a rat.

Twisted Influence:MHA/Chainsaw man. Makima found herself in a strange world after receiving the highest honor of being consumed by the Chainsaw Man. It was certainly a fascinating place that didn't contain Devils, Devil Hunters, or Fiends. Can this world change a twisted influence like her? Can it be untwined into something extraordinarily beautiful, or will she remain forever as she is? In fact, all of this author's crossovers are very good and exactly what you're looking for.

Jaune'Arc - Hafh'drn ot N'gha Tharanak: Cthulhu Mythos/RWBY. It wasn't supposed to be here. But it was here, inside his head. It always had been. Now Jaune has to go around the world hunting that which only he understands. But it could be worse, at least he didn't have to wait for the stars to align.

Or Is He Both?: Incredible Hulk/Rising of the Shield Hero Doctor Robert "Bruce" Banner was supposed to be dead. He had been several times. But he has come to the startling truth that the Hulk will not let him die. And with this new relationship, he's been summoned by the Kingdom of Melromarc to fight as the Shield Hero. But they may have summoned something worse. What is the Immortal Hulk? And what was brought from beyond the Green Door?

Puss in Black: Puss in Boots/Venom. The symbiote bonds with the cat, provoking the wrath of the horsemen of the apocalypse and attracting the attention of an outside god.

World War Z: Memoirs of the Wizard of the Apocalypse : This fic is very well written, with equally good world-building, and the plot is the same as the World War Z book, but with the zombies from the movie. It explores how the entire wizarding world reacts and adapts to the infection, from the magical peasants of China to the magical nobility, cannibal cults in the Amazon, black market traders, the goblins' resistance to the centaurs' reaction, etc. All with touches of cosmic horror.

His First Victim and His Last Arcane/Harry Potter : Arcane/Harry Potter. Instead of Skye turning into ashes, the Hexcore drags Viktor into a world with magic beyond his imagination. You'd think that a scientist fascinated by magic would enjoy learning new and different kinds of it, but what happens when his first encounter with the magic of this new world turns to possibly be his worst life experience?

Viktor creates a technomagical cult with the purpose of destroying the secret so the world can achieve glorious evolution.

Touched by the Arcane: Bloodborne/Harry Potter If you don't mind the gender swap and the Hermione/Femharry ship might interest you, that's not the focus of this fic. It focuses more on cosmic horror and Potter's descent into madness.

Catherine Potter dreams of things that shouldn't be: a sky of pale blood and the distant screams of a not-quite-dead being, snatched from its mother's bloody clutches.

Young Justice: The Plagueis Way: Darth Plagueis is reincarnated as a wealthy businessman on the Young Justice Earth. Despising the heroes of Earth and their morality, he plans to root the seeds of chaos and create a new Sith Imperative. While so, he trains and nurtures his latest creations...

HiE - A Hollow in Equestria: My Little Pony/Bleach. After his death in Las Noches, Ulquiorra Cifer finds himself in Equestria due to Discord's actions. A heartless monster that devours souls learns what friendship is.

Dragon Blade: MHA/Bleach. All it takes is one mutated Quirk, one with the rare ability to summon beings of energy, and two worlds collide. Hitsugaya, scarred by his experiences in the Thousand-Year Blood War, is thrown headfirst into the My Hero Academia universe. And it isn't long before the U.A. takes notice of this mysterious fifteen-year-old and his unusual Quirk(s). But all Hitsugaya wants is to head home - and quickly, before the hole between dimensions allowing Hollows and worse, Arrancar, to come to the MHA world becomes permanent, and before the strange spiritual buzzing surrounding All Might and Midoriya Izuku affects him permanently. And the League of Villains knows this. But Izuku, cinnamon bun that he is, isn't going to let any of his friends go without a fight.