Who was C.S. Lewis's older brother and biographer, commonly known as Warnie?

Warren Lewis was C.S. Lewis's older brother and was commonly known as Warnie.

Warren Hamilton Lewis was born in 1895, three years before C.S. Lewis. He served in the British Army during the First World War and later became a writer and editor. The brothers shared homes for much of their adult lives, first at Oxford and later at The Kilns.

Warnie kept detailed diaries and wrote historical works, especially on seventeenth-century France. After C.S. Lewis's death, he helped edit and preserve his brother's letters and papers, making him an important source for Lewis's biography and literary history.

Warren should not be confused with Albert James Lewis, the brothers' father, or William T. Kirkpatrick, one of Lewis's childhood tutors. Owen Barfield was a close friend and fellow member of the Inklings, not Lewis's brother.