Baldur
Married to the goddess Nanna, Baldur was invincible because that goddess Frigg had made all things swear not to harm him, except the mistletoe which she thought was too young to understand.
The gods revelled in Baldur's invincibility and threw axes and spears at thim for sport. Then Loki (the mischief maker) gave the bling god Hoder a sprig of mistletoe to throw. Loki guided Hoder's hand and Baldur was slain. All efforts to save him from the kingdom of Hel failed and he was never resurrected.
This tragedy showed the gods that not even they were immune from Wyrd (fate).
Adapted from 'A guide to the Gods' by Richard Carlyon
