What was C.S. Lewis’s full first name, reflected in the initials “C.S.”?

C.S. Lewis’s full first name was Clive Staples.

He was born Clive Staples Lewis in Belfast, Ireland, on 29 November 1898. “C.S.” became the literary form of his name, while friends and family often called him Jack, a nickname he adopted during childhood.

The nickname arose after the death of his childhood dog, Jacksie, in 1903. Lewis initially insisted on being called Jacksie, which was later shortened to Jack. This can cause confusion because biographies commonly refer to him as Jack Lewis even when discussing his published work.

Lewis became an author, literary scholar, Christian apologist, and broadcaster. His best-known books include The Chronicles of Narnia, Mere Christianity, and The Screwtape Letters. His initials are therefore much more familiar internationally than his given names, but the initials do not stand for a phrase such as “Christian Scholar.”