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).
The Letters of J. R. R. Tolkien
The Letters of J. R. R. Tolkien is a selection of J. R. R. Tolkien's letters published in 1981, edited by Tolkien's biographer Humphrey Carpenter assisted by Christopher Tolkien. The selection contains 354 letters, dating between October 1914, when Tolkien was an undergraduate at Oxford, and 29 August 1973, four days before his death.