The huldra - a mythological creature from Scandinavia. I'm from Sweden, and so I grew up with the Swedish version of the legend, which basically is - a lone man happens to be near a forest, a long time ago. Maybe a hundred years, maybe many hundreds. He's there because he's passing by, or working there. In this age there were few people in Sweden, and many dark forests.
It's growing late, dusk is falling.
Suddenly he sees a pale naked form just inside the forest - a woman it seems. An incredibly beautiful and attractive woman, calling to him. He approaches. By some strange trick of the light it looks like the woman isn't coming any closer... in fact she's receding. Without turning, always keeping her front towards him.
Because if he could see her back, he would see that she's hollow, like a hollowed out or rotten tree trunk.
He speeds up, she keeps receding.
After a while he's lost in the forest, night falls, the woman disappears without a trace, and no one sees the man ever again.