- A quick one that's often glossed over, but near the beginning of the movie, we get the wonderful sight of not one, but TWO ENTIRE INHABITED PLANETS BEING DESTROYED BY A BLACK HOLE. The inhabitants don't even have a chance to escape. Only one infant from each planet is able to make it off.
- Hal/Titan proves to be a scarier and more intimidating super villain than Megamind himself could ever hope to be.
Megamind: Well done! I thought that battle went really, really well! I mean, I have a few notes...
- Hal repeatedly tossing Roxanne several meters above the city.
- Titan/Tighten revealing he actually wants to kill Megamind instead of taking him to jail. Especially with his pupils glowing bright red. This forces Megamind to flee in absolute terror.
Megamind: But they can wait. You can take me to jail now.
Tighten: Oh, no, no, no, no. I was thinking more like the morgue! YOU'RE DEAD!
Megamind: Whoa, whoa, whoa, whoa, whoa! This isn't how you play the game!
Tighten: Game over!
Mayor: Titan has freed us!
- Later revealing his true nature to the Metro Citizens.
Tighten: Oh, I wouldn't say "freed". More like "under new management". (forcefully flicks the mayor with his finger, sending him flying)
- In a more down-to-earth sense of horror, the way Hal views Roxanne is very unnerving, particularly after he gets his powers and after she makes it clear how she doesn't like him. There are many creepy unstable men in Real Life who take rejection as poorly as he did, even to the point of taking the lives of others.
- Even before he becomes Tighten, Hal's interactions with Roxanne quickly stop being amusing and start being disturbing, with him acting like a complete creep and trying to manipulate her into getting to his house alone.
- The scene where Megamind seemingly kills Metro Man, or more specifically when it looks like Metro Man flew out only to have a skeleton under his clothes.
- Notably averted with the Dehydrator ray gun. It had potential to be quite unnerving, being essentially a Disintegrator Ray wielded by the hero of a kid's film, but the writers cleverly first gave the weapon a simple Reset Button, and then (arguably more important) diligently made sure that every time it was used on a living being, its effects were (at some later point) shown onscreen being undone, thus averting What Happened to the Mouse? and Fridge Horror via Offscreen Inertia.
Nightmare Fuel / Megamind