J.R.R. Tolkien used Finnish as the basis for his invented language Quenya.
Quenya is one of Tolkien’s most fully developed Elvish languages. Its grammar and sound patterns were strongly influenced by Finnish, while its vocabulary and history were shaped by Tolkien’s broader knowledge of comparative philology. Quenya is associated especially with the Ñoldor and with the ancient, formal speech of the Elves.
Tolkien also drew on other languages for his linguistic creations. Welsh influenced the sound and style of Sindarin, and elements of Latin, Greek, and Germanic languages contributed to his language-building work. Quenya is not simply Finnish with renamed words; it is a constructed language with its own grammar, vocabulary, and fictional development. In Middle-earth, it became less common as a daily spoken language in later periods but retained prestige in names, poetry, ceremony, and lore.