Balder

In Norse mythology, the best, wisest, and most loved of all the gods; son of Odin and Frigga; husband of Nanna. He was one of the Aesir (principal gods), but was killed unwittingly with a twig of mistletoe shot by Hodur, his blind brother; the tragedy was engineered by the god-giant Loki.

It had been foretold that the gods would be overthrown if Balder was struck down, so Frigga had made anything harmful, living or dead, swear not to injure him. Loki discovered that the mistletoe plant had been omitted, being considered too young and weak to be dangerous.