Creepy urban legends that may be real

What the title says, but REAL urban legends, for example Slender Man doesn't exist, only use an urban legend with eye witnesses.
Did you ever hear of the Bunnyman?
It talks about a man dress in a bunny costume that kills people near a bridge in Virginia, there were many eye witnesses so the Bunnyman really exists, unfortunately no one knew his identity or who he was.

Any other spooky legends?

Loch Ness Monster! Mah azz!