George MacDonald (1824-1905) was a Scottish Christian author who wrote fairy tales (sometimes allegorical) among other things. Below is a list of some of his books for children. They range from short stories to full books and are filled with memorable imagery.
The Princess and Curdie: full book, 256 pages (Puffin Classics version)
The Princess and the Goblin: full book, 241 pages (Puffin Classics version)
At the Back of the North Wind: 317 pages
The Light Princess: 110 short pages
The Golden Key (35 pages) and Other Stories (3 other short stories)
The Wise Woman (108 pages) and Other Stories (3 other short stories)