What was C.S. Lewis’s first name, Clive or Staples?

C.S. Lewis’s first name was Clive.

His full name was Clive Staples Lewis. The initials “C.S.” became his familiar author name, although friends and family used several forms of his name at different periods. As a boy, he reportedly adopted the nickname “Jack,” and that name remained important throughout his life.

Lewis’s middle name, Staples, came from his mother’s family name. Because his published works usually used initials, many readers never encountered his given name. The initials also gave his fiction and apologetic writing a formal, distinctive byline.

The name “Jack” can cause confusion: it was not his first name, and it was not a pen name used on his books. It was the personal nickname by which he was widely known to friends, colleagues, and members of his household.