4. Missingno
What is it: Even if you haven't ever played Pokémon, you may have heard of Missingno. It's a famous glitch Pokémon originating in Pokémon Red & Blue. It can be found by speaking to an old man in Viridian City in these games and then flying to Cinnabar Island and surfing up and down its coast by a mansion until you find it.
Why is it creepy: Well, it's a glitch for starters that really messes up your game. Nintendo even issued a statement on it. "MissingNO is a programming quirk, and not a real part of the game. When you get this, your game can perform strangely, and the graphics will often become scrambled. The MissingNO Pokémon is most often found after you perform the Fight Safari Zone Pokémon trick. To fix the scrambled graphics, try releasing the MissingNo Pokémon. If the problem persists, the only solution is to re-start your game. This means erasing your current game and starting a brand new one." Also, Missingno. is actually a Bird/Normal type. Bird isn't an actual type in the Pokémon games, making Missingno. even more odd and creepy. Simply encountering it will bump up the item in the sixth slot of the bag to 128, which many youngsters used for beefing their Pokémon up to level 100.