An elf is a creature of Germanic mythology. The elves were originally thought of 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, wherein a wise, immortal people named Elves have a significant role, elves became staple characters of modern fantasy.

Norse mythology

Although the concept itself is never clearly defined in the exact 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. The smith hero Völundr is identified as 'Ruler of Elves' (vísi álfa) and 'One among the Elven Folk' (álfa ljóði), in the poem Völundarkviða, whose later prose introduction also identifies him as the son of a king of 'Finnar', an Arctic people respected for their shamanic magic (most likely, the sami). 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 (seiðr), 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.

There are also in the Heimskringla and in The Saga of Thorstein, Viking's Son accounts of a line of local kings who ruled over Álfheim, corresponding to the modern Swedish province Bohuslän and Norwegian province Østfold, and since they had elven blood they were said to be more beautiful than most men.

The land governed by King Alf was called Alfheim, and all his offspring are related to the elves. They were fairer than any other people...

The last king is named Gandalf.

In addition to these human aspects, they are commonly described as semi-divine beings associated with fertility and the cult of the ancestors and ancestor worship. The notion of elves thus appears similar to the animistic belief in spirits of nature and of the deceased, common to nearly all human religions; this is also true for the Old Norse belief in dísir, fylgjur and vörðar ("follower" and "warden" spirits, respectively). Like spirits, the elves were not bound by physical limitations and could pass through walls and doors in the manner of ghosts, which happens in Norna-Gests þáttr. It is said that elves are the Germanic equivalent to the nymphs of Greek and Roman mythology, and vili and rusalki of Slavic mythology.Fact: date=May 2007