J.R.R. Tolkien created the original dust-jacket designs for The Hobbit and The Lord of the Rings.
Tolkien was not only a writer and philologist; he also drew maps, heraldic devices, lettering, illustrations, and designs connected with his stories. His original dust-jacket artwork helped establish a visual identity for the books before later publishers and film adaptations supplied their own imagery.
The first edition of The Hobbit used a design by Tolkien that included elements of the landscape and setting. For The Lord of the Rings, his designs likewise contributed to the presentation of Middle-earth and its geography. These works show that he considered visual form part of the process of world-building.
The answer is sometimes confused with Pauline Baynes, an illustrator associated with Tolkien’s later publications and with C.S. Lewis’s books. Baynes did illustrate Tolkien-related material, but the original dust-jacket designs for these major novels were Tolkien’s own. His artwork is now studied as evidence of how he imagined Middle-earth before adaptations.