What is C.S. Lewis famous poem?

C.S. Lewis is most famous for his prose works, particularly his children's fiction, like the Narnia series, and his Christian apologetics, such as Mere Christianity.

While he did write poetry, he's not known for any one particularly famous poem.

However, some of his poems that are well-regarded include:

* "The Weight of Glory" (from "The Weight of Glory and Other Addresses")

* "The Last Battle" (from "The Last Battle")

* "The Problem of Pain" (from "The Problem of Pain")

If you're interested in exploring his poetry, there are several collections available.