Elwin Ransom
Elwin Ransom may be based on C. S. Lewis' friend J. R. R. Tolkien ("Elwin" means "Elf friend" in Anglo-Saxon), though he seems to have autobiographical elements. In "That Hideous Strength" Ransom, with his royal charisma and matter-of-fact breezy acceptance of the supernatural, appears less like Tolkien than like Charles Williams (or some of the heroes in Williams' books).
Boxen (C. S. Lewis)
Boxen is a fictional world that C. S. Lewis ("Jack") and his brother W. H. Lewis ("Warren") created as children. The world of Boxen was created when Jack's stories about Animal-Land and Warnie's stories about India were brought together. In "Surprised by Joy", Jack explains that the union of Animal-Land and India took place "sometime in the late eighteenth century (their eighteenth century, not ours)".