The creature in Norse mythology known for being the wolf that will end the world during Ragnarok is Fenrir. Fenrir is a monstrous wolf, prophesied to break free from his chains during the apocalyptic events of Ragnarok. He is the son of the god Loki and is feared for his immense power and ferocity. Fenrir’s role signifies destruction and chaos, bringing doom to the gods, particularly Odin, during this cataclysmic battle. His fate is integral to Norse mythology, encapsulating the themes of fate and inevitability.