Harry Potter and the Chamber of Secrets (novel)/Nightmare Fuel


 * Hagrid, an 8.5 feet (2.6 m) tall half-giant who considers vicious and violent three-headed dogs that look like they were cast out of Hades 'cute', is absolutely horrified at the mention of Azkaban. It is not made clear by this book what is so frightening about Azkaban.
 * It's revealed in the next book. And it is most definitely the sort of thing that only the most dedicated of Death Seekers wouldn't be completely and utterly terrified of.
 * "Slytherin's gigantic stone face was moving... something was stirring inside the statue's mouth. Something was slithering up from its depths... Harry could almost see the giant serpent uncoiling itself from Slytherin's mouth... He heard Riddle's hissing voice: 'Kill him.'..."
 * An eleven-year old girl is possessed and writes in blood on the walls. The walls which mysteriously hiss at the protagonist. Hisses and moans about it being time to kill and eat. What's not freaky about that?
 * Even before the revelations of its true function in later books, Tom Riddle's diary is still deeply disturbing. Something about the fact that all the things the diary did were never really dissected and logically analyzed in-series made it all the more sickly dark, the same way that the simplistic, matter-of-fact way that dark things in children's stories and fairy tales are introduced are much more disturbing than deeply analyzed dark aspects of and occurrences in adult literature. The vagueness and mystery of the off-screen horrors combined with things that are perfectly logical but not all neatly tied up with an explanation—like the way the diary writes back, the ink gushing out of it, the effects it had on Harry, and the things Ginny wrote in it, and, most of all, the diary's total nondescript innocence and lack of physical threats, all have a creeping Grimm's Fairy Tales type of muted horror about it.
 * It's a Soul Jar with a copy of the mind of a genius, murderous seventeen year old sociopath with a deep-seated hatred of the racially "impure" and a willingness - no, eagerness - to wipe them off the face of the continent, if not the entire world. What about that isn't scary?
 * There is a giant snake. In a school. Filled with children. When you look at the snake, you either become a statue or die. And the gigantic, carnivorous basilisk: just what was it eating all those months? We only know about the victims whom it left petrified, not about whether or not anyone just plain disappeared...
 * Consider that Sally-Anne Perks does simply disappear between book 1 and 5.
 * Ginny writes blood on the walls. WHERE DID THE BLOOD COME FROM? She'd have to have a whole paint bucket of those just to write messages that big!
 * Presumably from all the school's roosters that she killed so that the giant snake would not hear them crow and die. There's another one right there: making an eleven year old Shrinking Violet kill anything, even animals.
 * Acromantulas. As if the fact that they're giant, man-eating spiders isn't enough, they also hunt in packs. And one of them nearly kills Ron.
 * Obliviate. That is all.
 * Lockhart mentions Entrancing Enchantments and love potions. Think about this when you remember that there is a book called Twelve Failsafe Ways to Charm Witches, that isn't all about wandwork, in a society where at least mild love potions are legal.