C.S. Lewis’s full first name was Clive. He was born Clive Staples Lewis in Belfast, Ireland, on 29 November 1898.
Lewis generally wrote and published under the initials “C.S.” rather than using his first name. The middle name Staples came from his mother’s surname, and “Lewis” was his family name. Friends and colleagues sometimes called him Jack, a nickname he adopted during childhood after the death of his dog, whom he had called Jacksie.
Lewis became known internationally as a literary scholar, Christian writer, essayist, and author of fiction. His best-known works include The Chronicles of Narnia, Mere Christianity, and The Screwtape Letters. Using initials gave his author name a formal, distinctive appearance, but it can lead readers to overlook the name Clive.
His brother Warren also used the family nickname Jack for him. The combination of his formal name and familiar nickname is one reason biographies often identify him as Clive Staples “Jack” Lewis.