Fantasy:
* The Chronicles of Narnia: This is arguably his most famous work, and it's a classic example of high fantasy, with talking animals, mythical creatures, and a battle between good and evil.
Christian Apologetics:
* Mere Christianity: This is a collection of radio broadcasts that explores the basics of Christian belief.
* The Problem of Pain: This book examines the issue of suffering and explores the Christian response to it.
* The Screwtape Letters: This novel is a satirical look at the temptations and struggles of human life from the perspective of a demon.
Science Fiction:
* Out of the Silent Planet: This is the first book in Lewis's "Space Trilogy," which explores themes of colonialism, religion, and the nature of humanity.
* Perelandra: This is the second book in the "Space Trilogy," which focuses on the fall of man and the role of free will.
* That Hideous Strength: This is the final book in the "Space Trilogy," which explores the themes of power, corruption, and the battle between good and evil.
Children's Literature:
* The Chronicles of Narnia is also a classic example of children's literature, though it contains themes that appeal to adults as well.
Literary Fiction:
* Till We Have Faces: This novel is a retelling of the Cupid and Psyche myth, and it explores themes of love, beauty, and the search for meaning.
It's important to note that many of Lewis's books blend genres. For example, "The Chronicles of Narnia" can be seen as both fantasy and children's literature.