Clive Staples Lewis (29 November 1898 – 22 November 1963), commonly referred to as C. S. Lewis, was an Irish author and scholar. Lewis is known for his work on medieval literature, Christian apologetics, literary criticism, and fiction. He is best known today for his series The Chronicles of Narnia.

Lewis was a close friend of J. R. R. Tolkien, the author of The Lord of the Rings. Both authors were leading figures in the English faculty at Oxford University and in the informal Oxford literary group known as the "Inklings". Due in part to Tolkien's influence, Lewis converted to Christianity, becoming "a very ordinary layman of the Church of England" (Lewis 1952, p. 6). His conversion had a profound effect on his work, and his wartime radio broadcasts on the subject of Christianity brought him wide acclaim. Late in life he married the American writer Joy Gresham, who died of bone cancer four years later at the age of 45.

Lewis's works have been translated into more than 30 languages and continue to sell more than a million copies a year; the books that comprise The Chronicles of Narnia have sold more than 100 million copies. A number of stage and screen adaptations of Lewis's works have also been produced, the most notable of which is the 2005 Disney film adaptation of The Lion, the Witch and the Wardrobe.