When I was little, I was told about Näkki (Neck in english). Näkki was an evil spirit who lured children to drown in wells. I always thought Näkki was an ugly troll, but I read about it and found out that in some legends Näkki could transform itself to an appealing male and sing to lure females. Read more:: http://en.wikipedia.org/wiki/Nix
All made in photoshop with default brushes. I used this stock picture as a reference http://tess-stock.deviantart.com/art/Restless-71088207