What was C.S. Lewis’s full first name, traditionally shortened to “Jack”?

C.S. Lewis’s first and middle names were Clive Staples.

Lewis was born in Belfast, Ireland, in 1898, and his birth name was Clive Staples Lewis. The initials “C.S.” became the name by which he was publicly known as a writer, scholar, and Christian apologist.

His friends and family usually called him “Jack,” a nickname he adopted in childhood after the death of a childhood dog named Jacksie. “Jack” is therefore not his legal first name. Lewis used several forms of his name in different settings, but his published works are overwhelmingly associated with C.S. Lewis.

He later became famous for The Chronicles of Narnia, theological works such as Mere Christianity, and literary scholarship. His name is sometimes confused with those of other British writers, but “Clive Staples” is the specific pair of names represented by the initials C.S.