What was C.S. Lewis’s full first name, rather than his initials?

C.S. Lewis’s full first name was Clive Staples. He was born Clive Staples Lewis in Belfast, Ireland, in 1898, and published nearly all of his major works under the initials C.S. Lewis.

Lewis disliked the name Clive during childhood and reportedly preferred the nickname “Jacks,” which developed into the name his friends used for him throughout his adult life. “Jacks” was also connected with an early childhood pet named Jacksie.

The initials helped give his writing a formal, memorable authorial identity, but they do not represent a middle name and surname only: “C.S.” expands to Clive Staples. His third name, Lewis, was his family surname.

Lewis’s naming history is sometimes confused with his brother Warren’s nickname, “Warnie,” or with the fictional names in his Narnia books. The author’s own name is the straightforward biographical fact behind the initials.