Ragnarök

The twilight of the gods will happen like this. There will be three years of terrible winters, and summers of black sunlight. People will lose all hope, and surrender to greed, incest and civil war. This will be the age of cruel winds, the age of people who become as wolves, who prey upon each other, who are no better than wild beasts. Twilight will come to the world, and the places where the humans live will fall into ruins, flaming briefly, then crashing down and crumbling into ash and devastation. Then, when the few remaining people are living like animals, the sun in the sky will vanish, as if eaten by a wolf, and the moon will be taken from us too, and no one will be able to see the stars any longer. Darkness will fill the air, like ashes, like mist.
Jörmungandr, the world serpent, will come lunging from the ocean, dragging the tides in and flooding the world. The wolf, giant Fenrir, will break his invisible chains. The skies will open and Surtr, the fire giant, will come flaming across the bridge to destroy the Gods. Óðinn, God of Knowledge will ride out of the gates of Valhöll to do battle for the last time against the wolf. Thór, God of Thunder will kill the serpent, but die from its venom. Surtr will spread fire across the Earth. At last, Fenrir will swallow the Allfather.