J.R.R. Tolkien created Quenya as the chief language of the Elves in Valinor.
Quenya is one of Tolkien’s most fully developed invented languages. Within the mythology, it is associated with the Elves who journeyed to Valinor and with the high Elves who later return to Middle-earth. Its sound and structure were influenced especially by Finnish, along with elements from other languages Tolkien knew or studied.
Quenya functions as a prestigious, ancient language in the stories, rather like a formal or classical language. Tolkien developed vocabulary, grammar, sound patterns, and historical relationships for it rather than treating it as a collection of decorative names. The famous Elvish greeting “Elen síla lúmenn’ omentielvo” is Quenya.
Sindarin is the other major Elvish language and is more commonly spoken by many Elves in Middle-earth. Adûnaic is associated with Númenor, while the Black Speech was created for servants of Sauron. Those distinctions make Quenya the specific answer here.