I have loved John Bauer since I lived in Sweden for six months when I was a kid. My parents give a collection of fairy tales illustrated by him. There is something about his trolls and his use of light and shadow.
This picture presents Bauer's artwork with short little narratives about trolls. There is what happens when a Friar tries to exile trolls from a forest. There is a princess who is captured by trolls but is able to save herself. There is a young boy who wants an enchanted frog to turn into something awesome - like a bear or a dragon. There is a wonderful bit about the artist and trolls.
If you know someone who loved the trolls in Frozen, you really should introduce them to Bauer.