J. R. R. Tolkien's The Lord of the Rings has been translated, with varying degrees of success, into dozens of languages from the original English. He was critical of some early versions, and made efforts to improve translation by providing a detailed "Guide to the Names in The Lord of the Rings", alongside an appendix "On Translation" in the book itself.

The complexity of the book, the nature of Tolkien's prose style with its archaisms, and the many names of characters and places combine to make translation into any language a challenge. A specific difficulty is the elaborate relationship between some of the real and invented languages used in the book. Westron, the common speech of Middle-earth, is "translated" as modern English; this stands in relation to Rohirric, an archaic language, which is represented by Old English, and the language of Dale, translated as Old Norse. The three real languages are related. The scholar of literature Thomas Honegger gives possible solutions for this in French and German, but suggests that the small amount of Old English is probably best left untranslated.

Tolkien, an expert in Germanic philology, scrutinized those that were under preparation during his lifetime, and made comments on early translations that reflect both the translation process and his work. To aid translators, and because he was unhappy with the work of early translators such as Åke Ohlmarks with his Swedish version, Tolkien wrote his "Guide" in 1967; it was released publicly in 1975 in A Tolkien Compass, and again, retranscribed, in the 2005 book The Lord of the Rings: A Reader's Companion.

Linguists have examined translations into several languages, noting the specific difficulties in each case, and the choices and errors that translators have made. Later versions in each language have benefited from the choice of adapting and correcting early versions, or of starting afresh. For instance, Margaret Carroux's careful German version was criticised by Wolfgang Krege, who made a new translation, for using a similar linguistic style for the speech of both elves and hobbits, despite the marked differences in the original, while Luis Domènech rendered the working class hobbits' non-standard English into accurate but standard Spanish. Translations have sometimes adopted a domesticating approach: for instance, the first Russian version to be printed substitutes secret police and armed escort for Tolkien's far gentler English policemen.

J. R. R. Tolkien (1892–1973) was an English Roman Catholic writer, poet, philologist, and academic, best known as the author of the high fantasy works The Hobbit and The Lord of the Rings.

The Lord of the Rings was published in 1954–1955; it was awarded the International Fantasy Award in 1957. The publication of the Ace Books and Ballantine paperbacks in the United States helped it to become immensely popular with a new generation in the 1960s. It has remained so ever since, judged by both sales and reader surveys.

Because The Lord of the Rings purports to be a translation of the fictitious Red Book of Westmarch, with the English language in the translation representing the Westron of the original, translators need to imitate the complex interplay between English and non-English (Elvish) nomenclature in the book. An additional difficulty is the presence of proper names in Old English and Old Norse. Tolkien chose to use Old English for names and some words of the Rohirrim, for example, "Théoden", King of Rohan: his name is simply a transliteration of Old English þēoden, "king". Similarly, he used Old Norse for "external" names of his Dwarves, such as "Thorin Oakenshield": both Þorinn and Eikinskjaldi are Dwarf-names from the Völuspá.

The relation of such names to English, within the history of English, and of the Germanic languages more generally, is intended to reflect the relation of the purported "original" names to Westron. The Tolkien scholar Tom Shippey states that Tolkien began with the words and names that he wanted, and invented parts of Middle-earth to resolve the linguistic puzzle he had accidentally created by using different European languages for those of peoples in his legendarium. The relationships cannot easily be replicated in translations of The Lord of the Rings.