The Midnight Library

A series of Horror novels for young adults. They have all been written by different authors under the pen names "Damian Graves" and "Nick Shadow." Quite a few books have been published, but only eight have been published for the 2000s era.

Each story revolves around the unfortunate tale of some kids who find themselves facing terrifying, supernatural threats, and each one leads up to a new ending that's bound to scar the reader's brains for quite some time. What makes the stories even more horrifying is that these are all kids suffering these fates. Eat your heart out, R.L. Stine.

Tropes used in The Midnight Library include:

And I Must Scream: The writers just love this trope. One story has a boy sealed in a mural, another has people turning into trees, and yet another has two kids turned into human sand sculptures.
Downer Ending: Nearly every single story.
Feathered Fiend:The parrot in "Man's Best Friend." Type A.
Wax Museum Morgue: "Blood and Sand."
Body Horror: "An Apple a Day." The protagonist tries to get back at his cruel neighbour for picking on his grandma by vandalizing his apple orchard. As a souvenir, he even eats one of the apples. The remainder of the story showcases him slowly transforming into an apple tree. Yeesh.
Psychic Powers: A more terrifying example in "Voices." The Girl in the story has the power to read other people's thoughts,but this backfires horribly when she begins reading too many minds at once.