The name of the giant serpent in Norse mythology that encircles the world is Jörmungandr. Also known as the World Serpent, this mythical creature is said to be so large it can coil around the Earth and grasp its own tail, symbolizing the cyclical nature of existence. Jörmungandr is a significant figure in Norse myths, particularly in connection with the prophesied events of Ragnarök, where it is destined to battle with Thor. This creature represents both the dangers of nature and the intertwining of fate and destiny.