Boxen was the imaginary world created by C.S. Lewis and his brother Warren during childhood.
The brothers combined two earlier inventions, Animal-Land and India, to form Boxen. They wrote stories, histories, and descriptions of its animal rulers and political events, producing an elaborate private mythology before Lewis became a professional author. Their childhood writing shows how seriously both boys treated world-building and invented literature.
Boxen is distinct from Narnia, which Lewis created decades later for The Chronicles of Narnia. It is also different from the planetary settings of his science-fiction trilogy. The Boxen material was not published as a major adult literary work during Lewis's lifetime, but it has become valuable evidence for biographers studying the origins of his imagination and narrative habits.