Tolkien disliked Shakespeare (somewhat), but the Bard still shaped Middle-earth

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Tolkien disliked Shakespeare so much that he once expressed regret at referring to one of Middle-earth’s races as Elves. While elves “is a word in ancestry and original meaning suitable enough,” he wrote to a friend in 1954, “the disastrous debasement of this word, in which Shakespeare played an unforgivable part, has really overloaded it with regrettable tones, which are too much to overcome.” Although he does not specify any plays, Tolkien must have had A Midsummer Night’s Dream and The Merry Wives of Windsor in mind. Both present elves as whimsical, lighthearted creatures who live in enchanted woods — a far cry from noble beings inhabiting the dark and dangerous forests of Middle-earth.

Ironically, the greatest influence Shakespeare had on The Lord of the Rings resulted from Tolkien wanting to rewrite a plot line he felt Shakespeare mishandled. In addition to the poorly worded prophecy concerning Macduff, Macbeth is also promised that he “shall never vanquished be until the Great Birnam Wood to high Dunsinane Hill shall come.” Later in the play, Macbeth watches his life flash before his eyes as an army of trees marches on Dunsinane. Except they aren’t trees; they are soldiers hiding underneath branches and foliage.

Tolkien was deeply disappointed at this revelation, which installed in him the desire to “devise a setting in which the trees might really march to war.” He did just that in The Two Towers when Middle-earth’s Ents — walking, talking tree-like creatures — besiege Saruman’s stronghold of Isengard to take revenge for the deforestation that fueled the wizard’s war machine.

...he may have had more in common with the Bard than he cared to admit. In addition to their mutual interest in the fantastical, both men were deeply connected to the English countryside — a country that gave them a deep appreciation for the simple things in life. For Shakespeare, this manifested in the bawdy humor and the unorthodox wisdom of characters such as Falstaff. For Tolkien, it found expression primarily through the Hobbits, whose humble existence rendered them immune to the corrupting power of the One Ring.