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).
Raymond Wilson Chambers
Chambers was a friend of J.R.R. Tolkien and their careers parallel each other at many points: both were Catholics (Tolkien a Roman and Chambers an Anglo-Catholic), scholars of Old English literature, both experienced the horrors of trench warfare in World War I (Chambers was too old to be an enlisted man, however), and both wrote influentially on "Beowulf" (Chambers' writings were one of the inspirations for Tolkien's ""). Thomas Shippey described Chambers as "a patron and supporter of Tolkien in his early years."