Loki Laufeyiarson, in Norse mythology is the "god" of mischief (actually, not a god at all but a giant, although mixing freely with the gods for a long time and even becoming Odin's foster-brother), a son of Farbauti and Laufey, and is described as the "contriver of all fraud."
The trickster god is a complex character, a master of guile and deception. He is also conceived of as a fire spirit, with all the potential for good and ill associated with fire. Loki is also an adept shape-shifter, with the ability to change both form (examples include transmogrification to a salmon, horse, bird, flea, etc.) and sex.
Having liaisons with giantesses was nothing unusual for gods in Norse mythology—both Odin and Freyr are good examples; and since Loki was actually a giant himself, there is nothing unusual about this activity. Together with Angerboda, he had three children:
- Jormungand, the sea-serpent;
- Fenrir the giant wolf preordained to slay Odin at the time of Ragnarok;
- Hel, the goddess of the realm of the dead.
On the way to Geirrod's, they stopped at the home of Grid, a giantess. She waited until Loki left the room then told Thor what was happening and gave him her iron gloves and magical belt and staff. Thor killed Geirrod, and all other frost giants he could find.
Loki was not so much a figure of unmitigated badness as a kind of celestial confidence trickster, who always managed to persuade the gods to give him another chance. Some anthropologists have compared him to Coyote, the trickster figure of the Native American mythology.
Loki occasionally works with the other gods. For example, he tricked Hrimthur, who built the walls around Asgard, out of being paid for his work by distracting his horse disguised as a mare—thereby he became the mother (!) of Odin's eight-legged horse Sleipnir. He also retrieved Odin's spear, Freyr's ship and Sif's wig from Dvalin, the dwarf, as well as rescuing Idun.
Loki overplayed his hand in this respect: disguised as a giantess, he arranged the murder of Baldur, although earlier versions of the myth, attributed to Saxo Grammaticus do not implicate Loki. Significantly, also, the poem in the Elder Edda most associated with Loki, the Lokasenna, does not directly implicate Loki in Baldur's death.
When the gods discovered that the giantess had been Loki in disguise, they hunted him down and bound him to three rocks. Then they tied a serpent above him, the venom of which dripped onto his face. His wife Sigyn (a goddess, not the giantess who was the mother of Loki's monster brood) gathered the venom in a bowl, but from time to time she had to turn away to empty it, at which point the poison would drip onto Loki, who writhed in pain, thus causing earthquakes. He would free himself, however, in time to attack the gods at Ragnarok.
Same as some other characters of Old Norse mythology, Loki has been adopted by later authors. In the Marvel Universe, for example, Loki is a supervillain who is the primarily enemy of his half-brother, Thor.
In Norse Mythology, Thor's parents were Odin and the Earth—nobody identical with any of Loki's parents, as mentioned above—so they weren't half-brothers. On the other hand Loki, as Odin's foster-brother, was in a way Thor's adopted uncle.
Loki Games was a manufacturer of computergames.
Loki was also the codename for a "Super Spectrum" computer developed by Sinclair Research. The name either came from the god Loki or as a play on "Low-cost Colour Computer" aka "LowCCC" or LC3. Loki was designed to be an Amiga-beater, but when Amstrad took over Sinclair in 1986 the project was cancelled. Two employees took the Loki technology with them and started Flare Technology and the Loki design was first intended to be launched as Konix Multisystem that never was released, but the technology finally was released as Atari Jaguar.
Some of the Loki technology was also used in the SAM Coupé.
Loki is also the name of a C++ software library developed by Andrei Alexandrescu. The library makes extensive use of templates to increase the flexibilty of implemented classes.