I don't know about creepiest ever, but recently I had a good scare... I was out camping and took an extra day at the campground so I was the only person left. Great big field, one tent. The park owner even offered to refund my money if I wanted to leave, but I was there on my own specifically to get away from the hustle and bustle, and I stayed the extra night.
I finished a novel I was working through and decided to finish the night playing call of Cthulhu on my iPad--not really scary but it sets a mood, you know. I fall asleep and wake up to something poking me in the back. I lie there : poke poke. It's in the middle of my back and I can here it scraping the bottom of my tent.
I look around without moving. My neighbors had told me about seeing some venomous snakes and I'm worried maybe something crawled in to get warm... I finally decided that it must be under the tent itself. Poke poke.
I sit up and the thing shimmies out from under the tent into the woods. For all I know it was a chipmunk or mole or something trying to keep warm, but it did give me a scare.