1.
Till We Have Faces by C.S. Lewis
This is a retelling of the myth of Cupid and Psyche from the perspective of Psyche's older sister.
2.
Descent into Hell by Charles Williams
This book by the second inkling on the list is a theological fantasy that deals with the themes of redemption and condemnation through the use of supernatural elements such as dopplegangers and ghosts. Certain concepts from Zoroastrianism and some images from Dante weave their way through the entire story.
3.
The Lord of the Rings by JRR Tolkien
The third inkling in the top three spots. I do not need to explain this book
.
4. The Chronicles of Thomas Covenant by Stephen R. Donaldson.
This series is also fairly well-known so I don't need to explain here either.
and Finally,
5.
The Voyage of St. Brendan the Abbot
This is a medieval journey tale about an Irish monk who searched for the land promised to the saints. His journeys around the Atlantic have such elements as having easter dinner on the back of a whale, a monk being taken by a demon and bursting into flames, and Judas Iscariot sitting on an Iceberg so that he could be released from his punishment one day each year. Some, like me, consider the story to be a fantastic retelling of actual events. Although maybe not as much a fantasy as the others, I would still classify it under this genre.