The Snow Queen by Hans Christian Andersen
Disney's Frozen originated as an adaptation of Snow Queen, but then drifted significantly. In this original novella, an evil troll creates a glass which distorts everything so only the bad is viewed. Fragments of this fall all over the world. One boy gets the shard in his heart and eye. He becomes cruel. Later he disappears with the snow queen who makes him forget about his past. The others go on adventures. Then in the end, his sister is able to melt his shard with love and return him back to normal. There are plenty of elements that were adopted by Disney, but this story is more complex.
