C.S. Lewis’s surname was Lewis when he used the pen name Clive Hamilton.
Lewis published Spirits in Bondage in 1919 under the name Clive Hamilton. The pseudonym combined his first name with a chosen surname, allowing the young writer to present the poetry separately from his personal identity. The book appeared before he became famous for Christian apologetics and Narnia.
His full birth name was Clive Staples Lewis, but friends and family generally called him Jack. The nickname came from a childhood association with a dog named Jacksie and eventually replaced “Clive” in everyday use. These different names can make Lewis’s early bibliography confusing.
The surname in the pen name was not Hamilton. Hamilton was part of the pseudonym, while Lewis was his actual family name. He later published under C.S. Lewis, the initials becoming the form most closely associated with his novels, scholarship, and religious writing.