In the summer of 1950 Tolkien received from Allen & Unwin, his publishers, proofs of the forthcoming second edition of The Hobbit (Letters no. 128). To his surprise he found that without consulting him they had removed the original Chapter 5, Riddles in the Dark, and substituted a new version, which he had sent to them three years earlier as 'a specimen of rewriting' (Letters no. 111) and which he had not originally meant to have published as written (no. 128). This new version, as many know, presents a very different portrayal of Gollum, Bilbo, and the Ring, one far more in keeping with the dark power invested in the Ring in The Lord of the Rings.** In a brilliant stroke Tolkien recast the version given in the first edition of The Hobbit as a lie Bilbo told Gandalf and the dwarves.
With mischief in his heart, however, Tolkien did not stop there. For in the Prologue we meet the following comment on The Red Book:
This [first] account Bilbo set down in his memoirs, and he seems never to have altered it himself, not even after the Council of Elrond. Evidently it still appeared in the original Red Book, as it did in several of the copies and abstracts. But many copies contain the true account (as an alternative), derived no doubt from notes by Frodo or Samwise, both of whom learned the truth, though they seem to have been unwilling to delete anything actually written by the old hobbit himself.(FR Pr. 13)
Publishers are much more pliant when they are your fictional characters. Take that, Rayner and Stanley Unwin!
** For a side by side presentation of Chapter 5 in the first (1937) and second (1951) editions, see here.