J.R.R. Tolkien based the fictional language Quenya partly on Finnish for Middle-earth.
Quenya is one of Tolkien’s Elvish languages and is associated especially with the High Elves. Tolkien designed it with a detailed sound system, grammar, vocabulary, and history rather than treating it as a collection of decorative words. Finnish was a major inspiration for its structure and appearance, although Quenya is not Finnish and cannot be translated simply by matching ordinary Finnish sentences.
Tolkien also developed Sindarin, another major Elvish language. Sindarin drew more strongly on Welsh influences, while Quenya has a more formal and archaic role in Tolkien’s imagined history. Characters use both languages in different contexts, and many names and titles in The Lord of the Rings come from them.
Readers sometimes identify Sindarin as the Finnish-inspired language because it is more visible in much of the narrative. The distinction matters: Quenya is the language linked most clearly to Tolkien’s study of Finnish.