Warren Hamilton Lewis (June 16, 1895-April 9, 1973) was the brother of noted British professor and author C. S. Lewis, and served as his secretary for the later years of C. S. Lewis's life. Warren Lewis was a supply officer in the British army during and after World War I, and after retiring in 1932 and coming to live with his brother in Oxford, was one of the founding members of the Inklings, an Oxford literary society.

As W. H. Lewis, he published several books of his own, including The Splendid Century: Life in the France of Louis XIV and Levantine Adventurer: The travels and missions of the Chevalier d'Arvieux, 1653-1697. He also edited the first published edition of C. S. Lewis's letters in 1966; later editions of these letters have been edited by Walter Hooper.