Starlit Heroics/Nightmare Fuel

This is definitely a violent series, written by a former Creepypasta writer but these just take the cake:

The Fenade ghosts. Good god, these things are creepy. Not only that, they have amples of Paranoia Fuel as they have the ability to go into your dreams just like Freddy Krueger and kill you. And they don't come alone...
Reversa. A Yandere of spectactular proportions, and her insanity is very... unsettling to say the least. She doesn't look bad, but trust me, with the things she does-- slicing off people's arms and heads to decorate her garden and hounding after the man she loves to the point where she'd do anything to herself to gain his love, you can just tell the girl's wrong in the head.
Vampire Remuses. Just when you thought vampires were getting soft after Twilight, these guys show up. Not only are these monsters turned into vampires, they're also hard to control even by the villains. The only person that can put them on a leash is Reversa. Let that sink in for just a second. Not only that, they're not even the worst kind of monster in the story.
Hollischennacht. Quite easily one of the most frightening people in the story. Why? He was based off of both Jedah Dohma and Alucard from Hellsing. And shows it.
Being an Abyss Knight and realizing that Nachzehrer are your fellow knights, except distorted beyond all recognition and corrupted by the dark powers of the Emptiness Shard. Doubles as Tear Jerker, since, you know, these might be your best friends you're hacking down, too.
- Same goes for you turning into one of them. Valiant Crystals made by Yami are actually Emptiness Shards in disguise, except they have a safety on them that makes them usable. However, if you overflow, lose control or go over the edge, the safety breaks and you lose all pretense of logic or emotion, turning into either a mindless monster or a former shadow of yourself, living in your own shattered world surrounded by the creatures you've crafted for yourself, all alone...
Just living in the planet of Xephixir in general. Sure, it's awesome and all with all the magic and the people in charge, but think about it. People die a lot, monsters roam the roads outside of the kingdoms or even a city, and worst of all, there's an evil organization plotting to either use you as a resource or as a tool, or just disposing you altogether. In fact, it's amazing the heroes are still trying their best to save everyone...
Linoura. Like Reversa (who is coincidentally her best friend), she's insane, but not in the love-crazed way. In fact, that makes it worse, as even a quirky a character as she is, Linoura is a definite psychopath, usually making monsters out of the sewed-together limbs of anything she and her lackey scavange up. To top it off, she was based off of Kefka.
Yami. Despite his cute cat-like appearance (excluding those ominous black-and-red eyes), the guy is a lunatic. First of all, he grew jealous of his brother Hikari and got angry at everyone else. It didn't take long before he snapped and tried to murder Hikari, only to have his body destroyed and his spirit sealed away into the Grandmaster Anthodia Stone. Even in his broken state, he looked for his brother and possessed his body, completely overwriting it and taking it for himself. DAMN. Not only that, he is the person where the Nachzehrer and the Emptiness Shards originated from, which eventually cursed the Abyss Knights he leads over...
The Deathmoon Family in general. They live on a living, crimson-red moon which is also where their headquarters is, and pretty much plan to destroy everyone and everything because the leaders, Puritus Bane and his wife Suprema, are so bat-shit crazy (as opposed to how they were before all this happened) that everything they do is pretty much to curse the heroes. It makes you feel sorry for them because of how low they've dropped, since you know, they were good guys like the Lunardream Family.
Idyuun. A massive creature not seen since Walpurgisnacht, but much more severe. She has been spreading around a disease that turns people into mindless Nachzehrer, and due to her utterly heartless nature, she treats the destruction of life as just a game for her own amusement. Not only that, she hides above the skies cloaked as invisible, so despite her massive size, you would never know where she is.
Something about the Valiant and Herota Crystals used by the Phastista and Melphi of the Lunardream Family and even the Legendary / Abyss Knights-- these contain the equivalent of souls in this world, which is a Life Core. It's sealed on the inside of the crystal. Now, there's not much to worry about, since these monster species can regenerate as long as their respective stone is intact. They're very fragile, though. However, it's much worse in the Abyss Knights case-- they're invincible as long as their stone is intact, even being able to survive if they were decapitated or even blown apart, which is something not even the Legendary Knights can be able to do. Not a pretty sight, I'm telling you now.
The creator has necrophobia and shows it, especially with the undead enemies.
The Sector of Evil Spirits, aka. this story's iteration of Hell. It's a dull, gray area filled to the brim with undead and bones, along with having seas of mist and a titan-sized zombie called Garfonze protecting the tower in the center of the entire place. Everyone that goes in or out that's a mortal turns into a sentient zombie like the population, regardless if they're dead or not. In a similar vein, the Chaotic Spirit Tomb, spider-infested catacombs where a volatile acid capable of melting skin off bones flows in one giant connected waterway in the place.