Finnish inspired much of the sound and structure of J.R.R. Tolkien’s Quenya.
Quenya is one of Tolkien’s principal Elvish languages and is associated especially with the High Elves. Tolkien was a professional philologist, so he built his invented languages with systematic sound patterns, grammar, vocabulary, and historical development rather than treating them as collections of decorative words.
Finnish made a particularly strong impression on him. Its distinctive phonology and grammar helped inspire the character of Quenya, although Quenya is not Finnish and cannot be translated simply by replacing words between the languages. Tolkien also drew on other linguistic sources, including Latin and Greek, while developing his fictional languages.
Sindarin, another major Elvish language, was influenced more strongly by Welsh in its sound. This distinction is a common source of confusion: Finnish is linked primarily with Quenya, whereas Welsh is the better-known influence on Sindarin. Tolkien’s linguistic interests were part of the foundation of his entire mythology, which he developed partly to give his languages imagined histories and communities.