C.S. Lewis’s surname before he adopted the pen name Clive Hamilton was Lewis.
Lewis was born Clive Staples Lewis, so “Lewis” was his family surname from birth. He published his first book of poetry, Spirits in Bondage, in 1919 under the pseudonym Clive Hamilton. The name combined his first name with a selected pen name and helped separate his literary identity from his personal life.
His later literary name, C.S. Lewis, came from his initials: Clive Staples Lewis. He became widely known by those initials, especially after publishing works of Christian apologetics, literary criticism, and fiction. The name C.S. Lewis is therefore not a separate family name but an abbreviated form of his given name and surname.
A frequent mistake is to treat “Staples” as Lewis’s surname. It was his middle name, inherited from his maternal grandmother’s family. Another possible confusion comes from the author’s use of different names at different stages of his career. “Clive Hamilton” belongs specifically to the 1919 poetry collection, while “C.S. Lewis” became the enduring public identity associated with Narnia and his other books.