Creatures of Germanic mythology. The elves were originally imagined as a race of minor nature and fertility gods, who are often pictured as youthful-seeming men and women of great beauty living in forests and underground places and caves, or in wells and springs. They have been portrayed to be long-lived or immortal and as beings of magical powers. Following J. R. R. Tolkien's influential The Lord of the Rings (in which a wise, angelic (and human-sized) people named Elves have a significant role) elves became staple characters of modern fantasy.

Elf can be pluralised as both elves and elfs. Something associated with elves or the qualities of elves is described by the adjectives elven, elvish, elfin or elfish. According to a convention of modern fantasy, the 'v' in elven or elvish refers to human-sized elves (who correspond more closely to those of the old Germanic paganism), 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).

Elves are also known as:

• Danish: Elver, elverfolk, huldrer or alfer (note alfer today translates to fairies).
• Dutch: elf, elfen, elven, alven.
• English: (Old English) ylf; (Middle English) albe; (Current) elf, elves.
• German: Elb (m) Elbe (f), Elben; Alb (m) "incubus"; from the English: Elf (m), Elfe (f), Elfen "fairies".
• Icelandic: álfar, álfafólk and huldufólk (hidden people).
• Old Norse: álfar.
• Swedish: alfer, alver or älvor (note Älvor today translates to fairies).
• Norwegian: alv, alven, alver, alvene / alvefolket (note alvefolket today translates to elfpeople)

The earliest preserved description of elves comes from Norse mythology. In Old Norse they are called álfar (singular, nominative case: álfr), and although no older or contemporary descriptions exist, the appearance of beings etymologically related to álfar in various later folklore strongly suggests that the belief in elves was common among all the Germanic tribes, and not limited solely to the ancient Scandinavians.

Although the concept itself is never clearly defined in the extant sources, the elves appear to have been conceived as powerful and beautiful human-sized beings. The myths about elves have never been recorded. Full-sized famous men could be elevated to the rank of elves after death, such as the petty king Olaf Geirstad-Elf, whereas the smith hero Wayland Smith was titled as "ruler of elves" while alive, in the Volundarkvida. In the Thidrek's Saga a human queen is surprised to learn that the lover who has made her pregnant is an elf and not a man. In the saga of Hrolf Kraki a king named Helgi rapes and impregnates an elf-woman clad in silk who is the most beautiful woman he has ever seen.

Crossbreeding was consequently possible between elves and humans in the Old Norse belief. The human queen who had an elvish lover bore the hero Högni, and the elf-woman who was raped by Helgi bore Skuld, who married Hjörvard, Hrólfr Kraki's killer. the saga of Hrolf Kraki adds that since Skuld was half-elven, she was very skilled in witchcraft, and this to the point that she was almost invincible in battle. When her warriors fell, she made them rise again to continue fighting. The only way to defeat her was to capture her before she could summon her armies, which included elvish warriors.