I'm sure this is more a thread for ghost stories and whatnot, but this is the scariest thing that's ever happened to me.
When I was a kid I lived in a rural place, because of that and the fact that this was the late 90s-early 2000s, my dad allowed me to play outside by myself. I had a neighbor quite close who was just a year or two younger than I am and she and I (both little girls, kind of pertinent I guess) would play in her yard often. At the end of her driveway was a huge tree that her dad had hung a big wooden circle from as a swing. One afternoon while we were playing on the swing, a car drove up and as it passed the bushes and trees at the end of their yard, just to where it could see us, it began to slow down but continued to pass. I was a smart kid and watched too many crime shows so I turned to my friend and told her I was scared that the driver wanted to hurt us. We ran up onto her back porch and hid behind the bushes where we could see but no one from the road could really see us. Sure enough, the car had turned around in the driveway just past mine and stopped right in front of the tree. Whoever was driving was holding something slightly out the window, I didn't see what it was but she was a little closer and says it was a gun. I found out years later a sex offender lives just down the road in the direction the car came from. To this day I get the creeps when I think about what could have happened to us had I not said something.