At HHN26, while the Tonight Show ride was still being built, my cousin and I were exiting either Ghost Town or Walking Dead. We round that corner at the end of NY, and I jump like 6 feet in the air because there was a man standing right on the other side of the wall staring at us. Turns out, it was just a Jimmy Fallon cutout on one of the construction walls.
I don't think it matters what's doing the scaring as long as it can catch you by surprise.