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).
An Experiment with Time
The ideas of Dunne also strongly influenced the unfinished novels "The Notion Club Papers" by J. R. R. Tolkien and "The Dark Tower" by C. S. Lewis. Both writers were members of the Inklings literary circle, and Tolkien also used Dunne's ideas about parallel time dimensions in developing the relationship between time in Middle Earth and "Lórien time".