Unmarked spoilers ahead.
General
- The main character is literally a skinless person that leaves blood everywhere he goes. Granted his simplistic design and the fact that he does not resemble real life living creatures a lot (having a square shape) help downplay the Body Horror aspect, but it's still a rather disturbing concept. And there's also the fact that he's weak to salt. Shudder.
- Dr. Fetus in general, who is literally a fetus in a jar. Since a lot of people find real life fetuses already creepy, the thought of this may be creepy for them. Granted, just like Meat Boy, his simple design help downplay the Nightmare Fuel, but that doesn't stop some artists from having their own portrayals of the character, including making him look more like a realistic fetus.
- Some fans even theorize that he's aborted, and if Edmund's affinity for the macabre is anything to go by, this may actually be true.
Super Meat Boy
- The Lil' Slugger Battle is a huge case of Mood Whiplash. Dr. Fetus sets the entire forest on fire and then chases you around with a giant chainsaw robot. The background is in a black-and-red color scheme and you're forced to witness cute forest animals being killed brutally. Despite being the first boss, it's definitely the darkest battle in the game.
- Some people, especially those who have a fear of needles, might be freaked out by the mountains of used syringes in the Hospital stage, and at best they can be Squick-ish.
- Chapter 4 takes place in Hell. And this is only the midpoint of the game.
- Black Maws are shadowy, Eldritch Abomination-like enemies who emerge from portals and charge at you while roaring, locking onto your every move. They are guaranteed to give a Jump Scare to new players. They're arguably even worse in the flash game, where their roars are borderline Ear Rape.
- On the subject of Hell enemies, there's also the Faceless Eyes that follow you everywhere you go with a deadly laser beam.
- Little Horn is a pretty intimidating boss, being the largest enemy in the game and having one of the scariest designs, with him literally being made out of all the Meat Boy corpses in Hell.
- World 5, Rapture. A ruined metropolis swarming with giant maggots and mutant freaks.
- Oobs, gonkish Airborne Mooks that chase you around in the Rapture stage. What makes them scary is how fast they are, and the fact that they can lunge at you without warning.
Super Meat Boy Forever
- There were some scrapped difficulty modes that were accompanied by pictures of Meat Boy getting increasingly mutilated with each difficulty. While "Hard" and "Mean" mode were relatively tame, "Cruel" mode fell into Body Horror territories, showing Meat Boy with tons of missing teeth, buzzsaws impaled into his body, and even an empty eye socket. Not to mention the fact that you can practically see in his expression that he's in a great amount of pain.
- There are ghost-like enemies called Spoops that look cute at first, but become gradually nightmarish-looking the more you attack them.
- Manic Manipulator. While silly-looking as merely a Brain in a Jar, once he reveals his monstrous form as shown above...
- The Other Side. Dear god, the Other Side. After time has been accidentally screwed up, Meat Boy and Bandage Girl are sent to a dark, scary Acid-Trip Dimension with contorted landscapes in the background. The world shown in the menu is different from the normally goofy-looking other planets, showing it to have voids for eyes and mouth.
