In Norse mythology, Jormungandr, also known as the Midgard Serpent, is a colossal sea serpent that encircles the world, Midgard. As the child of Loki, Jormungandr is prophesied to play a key role in Ragnarok, the end of the world, where he will rise from the sea and engage in a final battle with Thor, resulting in both their deaths. The serpent's immense size and association with the ocean make him a symbol of chaos and destruction in Norse lore.