C.S. Lewis’s first given name was Clive. He was born Clive Staples Lewis in Belfast, Ireland, on 29 November 1898, and later became widely known by his initials and surname rather than his first name.
Lewis’s childhood nickname was “Jack,” a name he chose for himself after the death of his dog, Jacksie. Family and friends continued to call him Jack for most of his life. The nickname is why biographies often introduce him as “Jack” Lewis, even though his published name was C.S. Lewis.
The initials C.S. stood for Clive Staples. “Staples” was his mother’s maiden name, and Lewis used the initials in his literary career. Readers sometimes assume the C stands for Charles because C.S. Lewis is frequently discussed alongside other Christian writers, but his birth name was Clive Staples Lewis. He died in Oxford on 22 November 1963, aged 64.