I think think someone made an SCP article around Herobrine. I swear I've heard of it before. I would be very surprised if no one has done that. Any way, Herobrine is not an SCP.
Siren Head was an SCP, but because Trevor Henderson made it, its SCP label was quickly taken down(that's what I believe happened, too lazy to google it)
That's the internet trying to cross and expand fandoms. That's how a lot of small fandoms die!
Some might just be trying to pass them off as their own creation though.
There was an article, but it had to be taken down due to legal reasons if I recall correctly. So yes, it was technically never an SCP, but it did have an article.
I am not brain dead, also I did hear that it was an SCP, I might be wrong tho, and the article that stated it might have been a troll one, but idk man.
Just because someone makes a fictional entity, and someone makes an SCP out of it, it does not make it an SCP in my eyes.
Crossing fandoms is how a lot of fandoms can die.
Caption this Meme 