C.S. Lewis’s surname was Lewis; the initials did not replace or conceal a different family name. His full birth name was Clive Staples Lewis, and “C.S. Lewis” is the author name by which he became known.
The initials combined his first name, Clive, and surname, Staples, while Lewis remained his family name. He used the initials in his published work, creating a concise pen name that became internationally recognizable. Friends and family commonly called him Jack rather than Clive.
The name “Staples” came from his mother’s family. Lewis’s father was Albert James Lewis, and his mother was Florence Augusta Hamilton Lewis. The family lived in Belfast during Lewis’s childhood before he later studied and worked in England.
Readers sometimes assume that “C.S.” represents two given names, as in some author names with middle initials. In Lewis’s case, the letters are taken from “Clive Staples,” not a double first name. His surname was consistently Lewis, including in the title of his books and academic records.