Here are my final thoughts on this discussion. I not only want to apologize for continuing this discussion, but also for the long read here.
Like others have said, no. Creepypastas are not real. Those "caught on camera" videos are just people in costumes and make up. Nothing more. What kind of a killer/monster would just stand around allowing themselves to be photographed?
Also, notice how these "sightings" take place at different parts of the world. How the Hell would these murderers go to different countries so quickly, and without being apprehended? I'm pretty sure if a wanted criminal went to buy an air plane ticket (or anything else for that matter), they would be arrested.
You also have to consider the fact that some stories are way too fantastical to have actually happened in real life. A lot of the stories on here have a few plot holes and things that couldn't actually happen (not that there's anything wrong with that). I'm going to use Jeff the Killer as an example because his story is pretty much the formula for most OCs, and because I don't want to rip on any particular user's story.
A lot of characters, like Jeff, undergo horrifying physical transformations which usually involves things that would either seriously injure or outright kill them. In real life Jeff's skin would be burnt pink and his hair would have been completely burned off. As far as injuries go, he cut his own mouth which would have lead to him losing a lot of blood and needing hospitalized, or it would have gotten infected and possibly killed him. He burned off his eyelids, which, if the fire wouldn't have blinded him, then the lack of protection would have dried his eyes out.
Many of these characters end up killing their parents and just running away without any way to support themselves. No money, no place to live, and no one to take care of them. The most likely scenario is that they would be living on the streets for a very short while before the police nab them and question them about their parents' deaths.
On the topic of police, there's no way these mass murderers would be able to outrun them for very long. These stories have the deus ex machina of police being useless. In real life, it probably wouldn't take very long for the police to track them down and stop them.
I mentioned about characters traveling from country to country in quick amounts of time. Kind of related, it's too unbelievable that Slender Man has a mansion in every forest in the world.
I do want to add that there's nothing wrong with stories not being believable, because who wants to read something realistic anyway? Reality is boring, that's why we read stories.
It's also dangerous to believe Creepypastas are real. Remember the Slender Stabbing, and that girl who killed herself to be with BEN?
These stories are just stories, written for the fun of it. They don't need to be real for you to enjoy them.