Horrifying novels for teens!

The Summoning by Kelley Armstrong

After fifteen-year-old Chloe starts seeing ghosts and is sent to Lyle House, a mysterious group home for mentally disturbed teenagers, she soon discovers that neither Lyle House nor its inhabitants are exactly what they seem, and that she and her new friends are in danger.  Sequels:  The Awakening and The Reckoning.

The Dead Boys by Royce Buckingham

Timid twelve-year-old Teddy Mathews and his mother move to a small, remote desert town in eastern Washington, where the tree next door, mutated by nuclear waste, eats children and the friends Teddy makes turn out to be dead.

Z by Michael Thomas Ford

In the year 2032, after a virus that turned people into zombies has been eradicated, Josh is invited to join an underground gaming society, where the gamers hunt zombies and the action is more dangerous than it seems.

Soul Enchilada by David Gill

When, after a demon appears to repossess her car, she discovers that both the car and her soul were given as collateral in a deal made with the Devil by her irrascible grandfather, eighteen-year-old Bug Smoot, given two-days' grace, tries to find ways to outsmart the Devil and his minions.

Once Dead, Twice Shy by Kim Harrison

Spunky teen Madison, though technically dead, uses a stolen amulet to retain the illusion of a body and help her in the struggle between Light and Dark reapers.  Sequels:  Early to Death, Early to Rise and Something Deadly This Way Comes.

Hold Me Closer, Necromancer by Lish McBride

Sam LaCroix, a Seattle fast-food worker and college dropout, discovers that he is a necromancer, part of a world of harbingers, werewolves, satyrs, and one particular necromancer who sees Sam as a threat to his lucrative business of raising the dead.  Sequel:  Necromancing the Stone.

Bonechiller by Graham McNamee

Four high school students face off against a soul-stealing beast that has been making young people disappear in their small Ontario, Canada, town for centuries.

Rot and Ruin by Jonathan Maberry

In a post-apocalyptic world where fences and border patrols guard the few people left from the zombies that have overtaken civilization, fifteen-year-old Benny Imura is finally convinced that he must follow in his older brother's footsteps and become a bounty hunter.  Sequels:  Dust and Decay , Flesh and Bone and Fire and Ash.

Daemon Hall by Andrew Nance

Famous horror story writer R. U. Tremblin comes to the town of Maplewood to hold a short story writing contest, offering the five finalists the chance to spend what turns out to be a terrifying--and deadly--night with him in a haunted house.  Sequel:  Return to Daemon Hall.

Sisters Red by Jackson Pearce

After a Fenris, or werewolf, killed their grandmother and almost killed them, sisters Scarlett and Rosie March devote themselves to hunting and killing the beasts that prey on teenaged girls, learning how to lure them with red cloaks and occasionally using the help of their old friend, Silas, the woodsman's son.

The Forest of Hands and Teeth by Carrie Ryan

Through twists and turns of fate, orphaned Mary seeks knowledge of life, love, and especially what lies beyond her walled village and the surrounding forest, where dwell the unconsecrated, aggressive flesh-eating people who were once dead.  Sequels:  The Dead-Tossed Waves and The Dark and Hollow Places.

Birth of a Killer by Darren Shan

When his cousin is murdered at the factory where they both work as child laborers, young Larten Crepsley commits a horrific act and must live on the run until he meets a vampire named Seba Nile who offers him protection and training as a vampire's assistant.  Sequels:  Ocean of Blood and Brothers to the Death.

Peeps by Scott Westerfeld

Cal Thompson is a carrier of a parasite that causes vampirism, and must hunt down all of the girlfriends he has unknowingly infected.  Sequel:  The Last Days.

The Monstrumologist by Rick Yancey

In 1888, twelve-year-old Will Henry chronicles his apprenticeship with Dr. Warthrop, a scientist who hunts and studies real-life monsters, as they discover and attempt to destroy a pod of Anthropophagi.  Printz Honor Book.  Sequels:  Curse of the Wendigo and The Isle of Blood.