What were the initials C.S. Lewis’s first and middle names abbreviated from?

C.S. Lewis’s initials abbreviated his first and middle names, Clive Staples.

He was born Clive Staples Lewis in Belfast in 1898. “C.S.” became the form used on his books and in public life, although family members and close friends generally called him Jack. That nickname originated in childhood and remained his preferred personal name.

Lewis’s name is sometimes confused with his literary pseudonym, Clive Hamilton. He used that name for his early allegorical novel The Pilgrim’s Regress, published in 1933. His later fiction, criticism, and Christian writing appeared under C.S. Lewis.

The initials therefore identify a writer whose private name and public author name were different. The distinction is especially useful when reading biographies, which may alternate between “Lewis” and “Jack.”