What was C.S. Lewis’s birth name, reflected in the initials of his pen name?

C.S. Lewis’s birth name was Clive Staples Lewis. He was born on 29 November 1898 in Belfast, Ireland, to Albert James Lewis and Florence Augusta Lewis.

The initials “C.S.” came directly from his first and middle names. His family commonly called him “Jack,” a nickname he adopted after the death of a childhood dog named Jacksie.

Lewis became known publicly by his initials rather than by his full given name. This can cause confusion because “C.S.” was not a separate pen name or an abbreviation of a different first name. He used the name on works ranging from Christian apologetics to literary scholarship and fiction.