Quenya is the fictional language developed by J.R.R. Tolkien with strong Finnish inspiration.
Tolkien began developing Quenya during the early twentieth century. He based much of its sound and grammatical character on Finnish, while also drawing on other languages and his own historical-linguistic ideas. In Tolkien’s mythology, Quenya is associated especially with the High Elves and is often called High-elven speech.
Quenya is not simply a collection of invented words. Tolkien created vocabulary, grammar, sound patterns, and a fictional history for it. This attention to language reflects his professional training as a philologist and his belief that languages could generate the histories and cultures of their speakers.
Sindarin is another major Elvish language, but Tolkien associated it more closely with Welsh inspiration. Khuzdul is the language of the Dwarves, while the Black Speech was created for the servants of Mordor. These distinctions make Quenya the specific answer here.