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).
George Watson (scholar)
He met C. S. Lewis at Oxford's Socratic Club in 1948 and attended his lectures. Later, he counted him among his finest professors and, after Watson joined Cambridge, among his colleagues. Among Watson's English students at St John's was Douglas Adams.