Finnish chiefly influenced J.R.R. Tolkien’s invented language Quenya.
Tolkien admired Finnish after encountering the Kalevala, Finland’s national epic, and used aspects of Finnish grammar and sound patterns while developing Quenya. He also drew on other languages, including Latin and Greek, so Quenya is not simply Finnish with new vocabulary.
Quenya is one of Tolkien’s major Elvish languages. In the fictional history of Middle-earth, it is associated especially with the High Elves and resembles a formal or classical language in its later use. Sindarin, another major Elvish language, was influenced more strongly by Welsh phonology.
This distinction is a common source of confusion. Finnish is the most frequently cited major influence on Quenya, while Welsh is usually connected with Sindarin. Tolkien’s language construction involved sound, grammar, historical change, and writing systems rather than word substitution alone.