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).
Forrest Reid
He was a close friend of Walter de la Mare, whom he first met in 1913, and about whose fiction he published a perceptive book in 1929. Reid was also an influence on novelist Stephen Gilbert, and had good connections to the Bloomsbury Group of writers. Reid was a founding member of the Imperial Art League (later the Artists League of Great Britain). Reid was also a close friend of Arthur Greeves, the artist known to be C. S. Lewis's best friend. Greeves painted several portraits of Reid, now all in the possession of the Royal Belfast Academical Institution.