C.S. Lewis’s first name was Clive. His full name was Clive Staples Lewis, and he was born in Belfast, Ireland, on 29 November 1898.
Lewis disliked the name Clive from childhood and adopted the nickname “Jack” after the death of his dog, Jacksie. Family and friends continued to call him Jack for the rest of his life. The initials in his published name came from his first and middle names: Clive Staples.
Lewis became known internationally as a writer of Christian apologetics, literary criticism, science fiction, and children’s fantasy. His best-known fictional works include The Chronicles of Narnia and the Ransom Trilogy. The name “C.S. Lewis” is therefore a shortened professional form rather than his complete given name.
A common mix-up is to treat Jack as a formal first name. It was Lewis’s preferred nickname, while Clive was the name recorded at birth.