Finnish inspired much of J.R.R. Tolkien’s constructed language Quenya.
Quenya is one of Tolkien’s most developed Elvish languages. He admired the sound and structure of Finnish, and Finnish grammar and vocabulary strongly influenced Quenya’s design. Tolkien encountered the Finnish national epic, the Kalevala, during his linguistic studies, and its style also contributed to his creative development.
Quenya is associated especially with the High Elves and functions in Tolkien’s stories as an ancient, formal, and literary language. It is not simply Finnish with invented words: Tolkien created its own grammar, history, dialect relationships, and fictional speakers.
Welsh was another major influence on Tolkien, particularly on Sindarin, the other prominent Elvish language in his fiction. Latin and Greek also mattered to his scholarly education, but they are not the usual answer when identifying Quenya’s principal real-world linguistic inspiration.