J.R.R. Tolkien based Quenya mainly on Finnish.
Quenya is one of Tolkien’s major constructed Elvish languages. Its sound and grammatical structure were strongly influenced by Finnish, while its vocabulary and history were developed as part of Tolkien’s larger mythology. He also drew inspiration from other languages, including Latin and Greek, but Finnish was the most important direct model for Quenya.
Tolkien treated his languages as historical systems that changed over time. Quenya was associated especially with the high Elves and was influenced by earlier forms such as the language spoken in Valinor. Sindarin, another major Elvish language, was developed with Welsh as a major influence.
The language is sometimes reduced to a collection of memorable phrases from the films, but Tolkien’s work on it was much deeper. He created sound patterns, inflections, vocabulary, and relationships between languages as part of the history of Arda.