C.S. Lewis’s first name was Clive. His full birth name was Clive Staples Lewis, and he was born in Belfast, Ireland, on 29 November 1898.
Lewis disliked the name Clive from childhood and preferred the nickname “Jack.” According to accounts of his early life, he adopted that name after the death of a childhood dog named Jacksie. The nickname eventually became the name used by friends and colleagues.
The initials “C.S.” remained his public literary signature, appearing on works such as The Problem of Pain, Mere Christianity, and The Chronicles of Narnia. “Staples” was his mother’s family name, which explains the middle name often included in biographical references. Lewis later became known as a literary scholar, Christian apologist, and novelist, but his birth certificate began with the comparatively ordinary name Clive.