Sif's golden hair, often read as the ripe wheatfield to Thor's fertilising thunderstorm, is the pivot of one of the most consequential myths. Loki, out of pure malice, sheared her bald as she slept. Facing Thor's fury, he promised better: hair of real gold that would grow like living hair, forged by the dwarves.
The Sons of Ivaldi made the hair — and Loki, unable to stop gambling, wagered his head with the dwarf brothers Brokkr and Sindri that they could not forge finer things. From that wager came Mjölnir, Draupnir, and Gullinbursti. Sif's restored hair thus stands at the head of the chain that armed the gods. She is the mother of Ullr and of Þrúðr, Thor's daughter.
The lady of the wheatfield
Snorri's Gylfaginning gives Sif a short, glowing entry: Thor's wife, fairest of women, with hair of gold; Skáldskaparmál adds that she may be called "the fair-haired goddess." Her name is the singular of a word meaning "affinity, kinship by marriage" — sif is the bond that weds two families together — which makes Thor's wife, at the level of the dictionary, the goddess of the marriage-tie itself. What she governed in cult, the meagre sources never say directly; the oldest and most attractive reading takes her hair as the ripe grainfield, golden, shorn at harvest, and growing again — the farmer's wife of the farmer's god, earth to his rain and thunder. It is an interpretation rather than an attested fact, and honest tellings flag it as such, but it has satisfied readers for centuries because it makes the one myth she owns click into place: cut the hair and the gold grows back, better than before.
Her household is Thor's hall Bilskírnir. Her son Ullr, the ski-god and archer, is Thor's stepson — Ullr's father is never named anywhere, one of the mythology's blank spaces — and her daughter with Thor is Þrúðr, "Strength," whose name matches her brothers Magni and Móði, Thor's virtues distributed among his children.
The shearing and the treasures
The story that made Sif immortal is told in Skáldskaparmál, and it begins with pure spite: Loki cut off all of Sif's hair "for love of mischief" — til lævísi — as she slept. Snorri does not explain further, and the silence has invited every reading from prank to violation; what matters to the plot is Thor's reaction. He caught Loki and would have broken every bone in him had Loki not sworn to get the black-elves to forge Sif a head of hair from gold that would grow like other hair.
Loki went down to the dwarves called the Sons of Ivaldi, and they made not only the hair but the ship Skíðblaðnir and the spear Gungnir. Then came the wager that armed Asgard: Loki bet his own head that the smith-brothers Brokkr and Sindri could not match those three treasures. Out of their forge came the boar Gullinbursti, the self-multiplying ring Draupnir — and Mjölnir, judged by the gods the best thing ever made, "the greatest defence against the frost-giants," short handle and all. Sif's new hair took root and grew, living gold; skalds ever after could call gold "Sif's hair." The economy of the myth is wonderful: a single act of malice against a sleeping woman ends with the gods holding the hammer that keeps the world safe. Sif's shorn head is, quite literally, the first cause of Asgard's arsenal.
Sif in the flytings
Sif speaks in exactly one poem. At the feast in Lokasenna, while Loki is savaging the assembled gods, she comes forward and pours him mead in a crystal cup, bidding him find her, at least, blameless. Loki takes the cup and answers that she would be — if she had not, as he claims, taken one lover: Loki himself. No other source corroborates the boast, and in the poem it reads as the flyter's standard weapon, the unfalsifiable slander. But the theme was in the air: in Hárbarðsljóð, the disguised ferryman (Odin at his nastiest) taunts Thor that Sif has a lover at home while her husband wastes his time arguing. And in Skáldskaparmál, when the giant Hrungnir, drunk in Asgard, bellows threats, he boasts he will carry off Freyja and Sif — the two beauties of the pantheon paired as prizes. Around Sif's fidelity the sources thus stage a little war of words that no text resolves; her own recorded gesture — the offered cup, the claim of blamelessness — is dignity under fire, and the duel with Hrungnir settles the giant's boast the way Thor settles things.
Saxo Grammaticus does not use her, and no place-names or cult sites are known: like several goddesses, Sif survives in literature only, her worship — if she had her own — invisible to archaeology.
In the primary sources
Skáldskaparmál in the Prose Edda carries the hair-cutting and the forging of the treasures, plus her kennings; Gylfaginning gives her portrait and family. In the Poetic Edda she appears in Lokasenna with the crystal cup and is name-dropped in Hárbarðsljóða and Þrymskviða (where Thor's bridal disguise is imagined against her golden standard). The prologue to Snorri's Edda, in its euhemerising mode, even equates her with the classical Sibyl — a learned medieval flourish, not myth.
Legacy
"Sif's hair" remained a skaldic formula for gold as long as skalds composed, and Scandinavian folk botany named a golden moss haddr Sifjar, "Sif's tresses." Her name lives on in Iceland as a woman's name, and modern astronomy has placed her on Venus and among the moons' catalogues of mythological names. She endures as the figure her myth made her: the injured party at the origin of the gods' greatest treasures, the harvest-gold that grows back every time it is cut.
Frequently asked questions
Who is Sif in Norse mythology?
The wife of Thor, famed as the fairest of women, with hair of living gold forged by dwarves after Loki sheared her natural hair. She is the mother of the ski-god Ullr and, with Thor, of the daughter Þrúðr.
Why did Loki cut off Sif's hair?
Snorri says only that he did it out of love of mischief — no fuller motive survives. Threatened by Thor with broken bones, Loki had the Sons of Ivaldi forge replacement hair of real gold that grew like living hair, and the ensuing wager with Brokkr and Sindri produced Mjölnir itself.
Is Sif a harvest goddess?
Very likely, though it is scholarly inference rather than an attested title. Her golden, shearable, regrowing hair has long been read as the ripe wheatfield paired with Thor's fertilising storms; the sources themselves describe only the hair and the marriage.
Who is the father of Sif's son Ullr?
Unknown. Ullr is called Thor's stepson, so Sif bore him before or outside her marriage to Thor, but no surviving source names the father — one of Norse mythology's many lost threads.