Spring Heeled Jack was responsible for personal terror in my youth:
When I was around 10 years old, I went to stay the weekend with my uncle and aunt.
As is always my habit, I was the last to go to bed as I enjoyed staying up to the wee hours of the morning.
I decided to read a book on urban-legends/myths, and lo and behold, came across the story of “Spring Heeled Jack”.
Needless to say, it was a sleepless night, especially considering the room I was staying in had no curtains and I was CERTAIN that Mr. Jack was peering in on me everytime I closed my eyes...
Even if it is BS - and by that I mean it is a figment of people's imagination it is fascinating to me because people imagine the same thing seperated by thousands of miles and decades of time.