Ragnarök is a series of events in Norse mythology that signifies the end of the world and the death of many gods. It includes a great battle, natural disasters, and the submersion of the Earth in water. Key figures involved in Ragnarök include Odin, Thor, Loki, and Fenrir, among others. During Ragnarök, it is foretold that Thor will fight the serpent Jörmungandr, while Odin will face Fenrir. After the destruction, the world is expected to rise again, renewed and fertile, with surviving gods and two human survivors who will repopulate the Earth.