What was the pen name C.S. Lewis used for several early works?

C.S. Lewis used the pen name Clive Hamilton for several early works.

Lewis published his 1919 poetry collection Spirits in Bondage under the name Clive Hamilton. He also used that name for Dymer, a narrative poem published in 1926. The pseudonym combined his preferred first name, Clive, with Hamilton, a family name connected to his mother’s side.

The choice helped distinguish Lewis's early poetry from his later public identity as a scholar and Christian writer. After Dymer, he increasingly published under his initials, C.S. Lewis, a name that eventually became associated with fiction, literary criticism, apologetics, and devotional writing.

The pen name is easy to confuse with Lewis's legal name, Clive Staples Lewis. “Jack” was the personal nickname used by friends and family, not a publishing pseudonym. His initials became especially recognizable after the success of The Problem of Pain, The Screwtape Letters, and The Chronicles of Narnia.