- Rumors of the "White Lady" of Perion, a supposed character that would appear in Perion's town map very rarely. Some rumors suggest that Nexon put her there on purpose to honor someone who had died, some believe it was a bot-catching character, others believe it may have been a glitch(as the character appeared rendered from player sprites), while yet others believe it was a complete hoax. The character appears to be that of a female Warrior class with solid white skin and hair. Rumors have persisted for some time and there are even faked videos on Youtube, some of which are downright scary. Some claims suggest that clicking on the character brings up a player info box with an infinity symbol for the level and no number stats listed. No evidence of the character in the game's files has been found but if it was called from player sprites as most claim, then there would be no specific NPC sprites. But as of Big Bang and the new town maps, if the character was genuine, it may have been dummied out from appearing.
- The Black Mage himself, who encases the heroes who fought him in ice, and in the future manages to corrupt Empress Cygnus and her knights and conquer all of Maple World in a bad future. He also is responsible for causing a cataclysm that dramatically changed Victoria Island once the Black Wings managed to remove his seal.
- The boss Alishar. At first glance◊, it's already scary-looking: a mutant whale with glowing eyes, huge teeth, prominent nipples, and tiny legs. Then it flips over and attacks. Those "nipples" are eyes to a demonic beast.
- From Alishar's Death Magic in iTCG: "His clock knows the hour of your death."
- The Soul Teddy monsters. The first one, Soul Teddy◊, doesn't seem so bad. The Master Soul Teddy◊ is still more cute than scary. Then you run into Death Teddy◊ and Master Death Teddy◊. Their corruption of a teddy bear as a comfort object is what hits hardest.
- Little girl marionettes◊ and flying head marionettes◊, both which cry like little girls when defeated. You really have to watch it to feel it.
- It's worse if one knows the story behind the mansion and its people. The dolls are modeled after the daughter of the man who ran the toy-making shop in the mansion (it was noted that these dolls looked creepy enough even before they were possessed). Sophilia was climbing up a chimney and fell to her death, causing her father to lock himself in his factory and eventually starve, and her butler to be overwhelmed by guilt. When the mansion was first released, those that got in could converse with the ghosts of the inhabitants, who were, aside from a few, unaware that they had been dead for what was probably decades. Now imagine that sweet, innocent Sophilia, who just wants her first doll, some candy, and to see her father, then imagine her wailing like the death cries of the dolls.
- From Bad to Worse is practically a theme of the place! Poor Killian, oh yes, poor Killian, stuck roaming the woods which moan in the night, headless and an eternal slave of the Black Magician. THAT was a Moral Event Horizon crossing for the Black Magician, condemning someone to And I Must Scream for eternity.
- Some of the tree trunk interiors in the Ellinia woods simply look cavernous with a lot of tree bark to jump on. Some of the trunk interiors in the higher parts of the woods, however, look like something out of an alien horror film.
- Some regular monsters, like Dreamy Ghosts and Eyes of Time look kind of cute, until they actually attack you and put on a rather horrific Game Face.
- When killed, Octopus monsters fall down while their skin rips open exposing their flesh as their eyeballs drop from their orbits. This being the most disturbing animation in the game.
- The Madhouse is one Nightmare Fuel after another. First off, if time runs out, the last thing you see before being kicked out of the dungeon is a glaring blue eye (presumably The Mole Sean's, right before she strikes with a skull for a pupil and a scream, presumably yours. If you enter a room without a light or take the wrong medicine, you wind up in a room where you find one of your friends being tortured. (Worse, the devices the doctors and orderlies are using on them? Those are chairs you can get from the Vending Machine if you ever want to see your character like that.) Not to mention, as you put together Chloe's diary, you start to learn, one bit at a time, just what happened to her; and when compared to Sean's brief diary, found in the epilogue, you find her point of view, and discover the truth, when pieced together, the truth of the killer's identity should come as a shock, along with the realization that you ''killed her.
- These mannequin monsters ◊ ◊ ◊ are...kind of unsettling
- The Spikes of Doom throughout the game can range anywhere from small and annoying to large and terrifying-looking.
- In the Kinesis storyline, the six civilians that he rescues before level 60 are scared to death when he finds them - a couple even think that they're in Hell, literally. Some are children. The true Fridge Horror of this situation comes later, when you realize that the six you save are only six of thousand still missing, who have to wait to be rescued.
- The xenodroids in Black Heaven and the Scrapyard. Those guys just aren't right. (Although, storylines show they're just as capable of sentience and emotion as the other robots.)
Nightmare Fuel / MapleStory
Despite the innocent-looking game (or maybe moreso because of it), there's some frightening stuff.