J.R.R. Tolkien based Quenya primarily on Finnish.
Quenya is one of the major Elvish languages in Tolkien’s legendarium. He developed its sound and grammar as part of his lifelong interest in constructed languages, and Finnish strongly influenced its structure and appearance. Quenya is associated especially with the High Elves.
Sindarin is another major Elvish language, but Tolkien drew much of its inspiration from Welsh rather than Finnish. This distinction is a frequent source of confusion because Quenya and Sindarin are both presented as Elvish languages in The Lord of the Rings.
Tolkien’s languages were not merely collections of invented words. He created historical relationships, sound changes, and writing systems for them. His linguistic work often came first: stories and mythology grew around the languages, giving the fictional cultures that used them a deeper history.