C.S. Lewis was a British writer and scholar best known for his works in fiction and Christian apologetics. His most famous books include The Chronicles of Narnia, a series of seven fantasy novels that explore themes of good versus evil, faith, and redemption. Another significant work is Mere Christianity, which presents a rational case for Christianity and discusses moral principles. In addition to fiction and apologetics, Lewis wrote scholarly works on literature and philosophy. His essays and books, such as The Screwtape Letters and The Abolition of Man, delve into moral and ethical issues, showcasing his deep understanding of human nature and belief systems.