Forseti (pronounced “for-SET-ee;” Old Norse Forseti, “Chairman”) is an obscure pre-Christian Norse god. He is mentioned only twice in Old Norse literature. The first mention comes from the 15th stanza of the Grímnismál, one of the poems in the Poetic Edda. There, it’s said that Forseti’s dwelling-place, Glitnir, is a resplendent hall made of gold and silver, and that he settles disputes. He thus seems to be the divine equivalent of and model for the human “lawspeaker” (lögsögumaðr), the ceremonial head of the þing, the Scandinavian legal assembly. The lawspeaker often acted as a judge who decided the outcome of disputes in accordance with the law.
That’s the extent of reliable, relatively unambiguous information concerning Forseti that we have from any primary source. The sole other mention of him in Old Norse literature comes from the Prose Edda of Snorri Sturluson. The passage reads like a flippant embellishment on the Grímnismál. Snorri, ever concerned with tidiness at the expense of accuracy, claims, with no apparent basis, that Forseti is the son of Baldr and Baldr’s wife, Nanna. As I’ve discussed in numerous other articles on this site (do a search if you’re interested), Snorri can’t be taken at face value, and there’s no reason to assume that his remarks on Forseti’s parentage are anything but his own invention.
Other possible references to Forseti from other kinds of sources are also ambiguous and problematic.
According to Alcuin’s eighth-century Life of St. Willibrord, Willibrord once visited an island between Denmark and Frisia. There was a holy spring on the island from which people obtained water, and they did so in silence due to the holiness of the place. The Life records that the island was named Fositesland after the god who was worshipped there. This Fosite could be Forseti, but this is far from certain, and if it were the case, it would raise additional problems with the meaning and etymology of Forseti’s name.
In one medieval account of the origin of Frisian law, twelve lawmakers were set adrift at sea as a punishment by Charles the Great. They prayed to the Christian god for assistance, and their prayers were answered when a thirteenth man carrying a golden axe mysteriously appeared among them. He used his axe to row the ship to land, and when they reached land, he threw the axe on the ground, and a spring gushed forth from the spot where it landed. This thirteenth man taught them the laws they needed to know, then vanished.
While the element of the holy (or at least mysterious) spring in both texts could point to a common tradition linking Forseti and holy springs, and the golden axe of the second text could be connected to Forseti’s golden hall, these correspondences are highly tenuous and demonstrate nothing conclusively. It’s possible that the thirteenth man was the god Forseti, but it’s more likely that he was Christ, since he came in answer to Christian prayers, and was the thirteenth man among twelve followers, like Jesus and his apostles.
Unfortunately, then, the one passing reference to Forseti in the Grímnismál provides the only reasonably trustworthy information we have about Forseti as he was understood in heathen times.
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 The Poetic Edda. Grímnismál, stanza 15.
 Snorri Sturluson. The Prose Edda. Gylfaginning, chapter 31.
 Ellis-Davidson, Hilda Roderick. 1964. Gods and Myths of Northern Europe. p. 171.
 Simek, Rudolf. 1993. Dictionary of Northern Mythology. Translated by Angela Hall. p. 88-89.
 Ellis-Davidson, Hilda Roderick. 1964. Gods and Myths of Northern Europe. p. 171-172.