Quenya (pronounced [ˈkʷwɛnja]) is a constructed language, one of those devised by J. R. R. Tolkien for the Elves in his Middle-earth fiction.

Tolkien began devising the language around 1910, and restructured its grammar several times until it reached its final state. The vocabulary remained relatively stable throughout the creation process. He successively changed the language's name from Elfin and Qenya to the eventual Quenya. Finnish had been a major source of inspiration, but Tolkien was also fluent in Latin and Old English, and was familiar with Greek, Welsh (the primary inspiration for Sindarin, Tolkien's other major Elvish language), and other ancient Germanic languages, particularly Gothic, during his development of Quenya.

Tolkien developed a complex internal history of characters to speak his Elvish languages in their own fictional universe. He felt that his languages changed and developed over time, as did the historical languages which he studied professionally—not in a vacuum, but as a result of the migrations and interactions of the peoples who spoke them.

Within Tolkien's legendarium, Quenya is one of the many Elvish languages spoken by the immortal Elves, called Quendi ('speakers') in Quenya. Quenya translates as simply "language" or, in contrast to other tongues that the Elves met later in their long history, "elf-language". After the Elves divided, Quenya originated as the speech of two clans of "High Elves" or Eldar, the Noldor and the Vanyar, who left Middle-earth to live in Eldamar ("Elvenhome"), in Valinor, the land of the immortal and God-like Valar. Of these two groups of Elves, most of the Noldor returned to Middle-earth where they met the Sindarin-speaking Grey-elves. The Noldor eventually adopted Sindarin and used Quenya primarily as a ritual or poetic language, whereas the Vanyar who stayed behind in Eldamar retained the use of Quenya.

In this way, the Quenya language was symbolic of the high status of the Elves, the firstborn of the races of Middle-earth, because of their close connection to Valinor, and its decreasing use also became symbolic of the slowly declining Elvish culture in Middle-earth. In the Second Age of Middle-earth's chronology the Men of Númenor learnt the Quenya tongue. In the Third Age, the time of the setting of The Lord of the Rings, Quenya was learnt as a second language by all Elves of Noldorin origin, and it continued to be used in spoken and written form, but their mother-tongue was the Sindarin of the Grey-elves. As the Noldor remained in Middle-earth, their Noldorin dialect of Quenya also gradually diverged from the Vanyarin dialect spoken in Valinor, undergoing both sound changes and grammatical changes.

The Quenya language featured prominently in Tolkien's The Lord of the Rings, as well as in his posthumously published history of Middle-earth The Silmarillion. The longest text in Quenya published by Tolkien during his lifetime is the poem "Namárië"; other published texts are no longer than a few sentences. At his death, Tolkien left behind a number of unpublished writings on Quenya, and later Tolkien scholars have prepared his notes and unpublished manuscripts for publication in the journals Parma Eldalamberon and Vinyar Tengwar, also publishing scholarly and linguistic analyses of the language. Tolkien never created enough vocabulary to make it possible to converse in Quenya, although fans have been writing poetry and prose in Quenya since the 1970s. This has required conjecture and the need to devise new words, in effect developing a kind of neo-Quenya language.

J. R. R. Tolkien began to construct his first Elvish tongue c. 1910–1911 while he was at the King Edward's School, Birmingham. He later called it Qenya (c. 1915), and later changed the spelling to Quenya. He was then already familiar with Latin, Greek, Spanish, and several ancient Germanic languages, such as Gothic, Old Norse, and Old English. He had invented several cryptographic codes, and two or three constructed languages. Tolkien took an interest in the Finnish mythology of the Kalevala, then became acquainted with Finnish, which he found to provide an aesthetically pleasing inspiration for his High-elvish language. Many years later, he wrote: "It was like discovering a complete wine-cellar filled with bottles of an amazing wine of a kind and flavour never tasted before. It quite intoxicated me." Regarding the inspiration for Quenya, Tolkien wrote that:

The ingredients in Quenya are various, but worked out into a self-consistent character not precisely like any language that I know. Finnish, which I came across when I had first begun to construct a 'mythology' was a dominant influence, but that has been much reduced [now in late Quenya]. It survives in some features: such as the absence of any consonant combinations initially, the absence of the voiced stops b, d, g (except in mb, nd, ng, ld, rd, which are favoured) and the fondness for the ending -inen, -ainen, -oinen, also in some points of grammar, such as the inflexional endings -sse (rest at or in), -nna (movement to, towards), and -llo (movement from); the personal possessives are also expressed by suffixes; there is no gender.