He was the fairest, the gentlest, the purest – and yet it was he whom death struck. The legend of Balder is the most moving story in all of Norse mythology: a light that goes out, and the vain grief of an entire world.
Balder (Old Norse Baldr) is the son of Odin and Frigg, husband of Nanna and father of Forseti. Snorri describes him as so radiant that light shines from him; he is the wisest, kindest and most eloquent of the Æsir – but, Snorri adds almost wistfully, none of his judgements holds. His hall is called Breidablik („broad-gleaming“), the purest place, where nothing impure can happen.
The story begins with sleep: Balder is tormented by dark dreams of his own death. The gods take counsel. Frigg then extracts an oath from all things in the world never to harm Balder – fire and water, iron and ore, stones, sicknesses, animals and serpents. Only one young plant does she pass over, the mistletoe, because it seems to her too young and insignificant.
Now that nothing can hurt Balder any longer, the gods make a game of it: they throw everything at him, and it all bounces off harmlessly. A cheerful image of the invulnerability of the light – until Loki discovers the one gap.
Loki fashions an arrow (or twig) from the mistletoe and presses it into the hand of the blind god Höðr, Balder’s brother. Unsuspecting, Höðr throws it, guided by Loki – and the mistletoe pierces Balder. The shining god falls dead to the ground. It is the greatest grief that ever came upon gods and men. Nanna, his wife, dies of sorrow and is burned with him on the ship Hringhorni; Odin lays the ring Draupnir on the pyre beside him.
„I saw for Balder,
the bleeding god,
Odin’s child,
the fate concealed.“
— Völuspá, st. 31 (after Karl Simrock, 1851, public domain)
Frigg does not give up. The messenger Hermod rides down to Hel on Odin’s steed Sleipnir to bring Balder back. Hel sets one condition: if everything in the world weeps for Balder, he may return. And almost everything weeps – people, animals, stones, trees. Only a giantess named Þökk (Loki in disguise) stays hard: „Þökk will weep with dry tears.“ So Balder remains in the realm of the dead – until after Ragnarök.

Frigg · Hel · Loki · Sigyn & Loki’s Punishment · What comes after Ragnarök? · Draupnir & the Treasures.
Poetic Edda: Völuspá (sts. 31–33), Baldrs draumar. Snorri Sturluson, Prose Edda (Gylfaginning: Balder’s death, Hermod’s ride), c. 1220. Saxo Grammaticus, Gesta Danorum (heroic version), c. 1200. English public domain: Henry Adams Bellows (1923). Research: Rudolf Simek, Dictionary of Northern Mythology; John Lindow, Murder and Vengeance among the Gods (1997).