Surtr is the fire-giant of Norse myth, and his significance is eschatological: he is the appointed destroyer of the world at Ragnarok. He stands guard at the border of Muspelheim, the primordial realm of flame in the far south, one of the two elemental worlds, fire and ice, whose meeting the Eddas make the origin of creation itself, wielding a sword that blazes brighter than the sun. He is among the oldest beings in the cosmos, present before the gods, and he is destined to outlast them.
At the end of the world, the sources foretell, Surtr will ride out from the south at the head of the sons of Muspell; the rainbow bridge Bifrost will break beneath them; he will meet and kill the god Freyr in the final battle; and then he will fling fire across the whole of creation, and the nine worlds will burn. Yet the Norse conception of the end is not simple annihilation: from the ashes a renewed earth is said to rise. Surtr thus frames the Norse cosmos at both ends, the fire present at its kindling and the fire that consumes it, the destined agent of a destruction that is also, in the myth's cyclical vision, a clearing for what comes after.