An elf is a mythical creature of Germanic mythology/paganism which still survives in northern European folklore. In Norse mythology they were originally a race of minor gods of nature and fertility. Elves are often pictured as youthful-seeming men and women of great beauty living in forests and other natural places, underground, or in wells and springs. They have been portrayed to be long-lived or immortal and they have magical powers attributed to them. Following the success of J. R. R. Tolkien's epic work The Lord of the Rings—wherein a wise, angelic people named Elves play a significant role—they have become staple characters of modern fantasy (see: Elves in fantasy fiction and games).

Elf can be pluralized both as elves and elfs. Something associated with elves or the qualities of elves is described by the adjectives elven, elvish, elfin or elfish. A convention of modern fantasy usage is: the v in elven or elvish refers to human-sized elves (who correspond more closely to the mythology of the Viking Era), whereas the f in elfin or elfish refers to tiny-sized elfs (who correspond more closely to the folklore of the Renaissance and Romantic Eras).