Jörmungandr

Jormungand (pronounced “YOUR-mun-gand;” Old Norse Jörmungandr, “Great Beast”), also called the "World Serpent,” is a snake or dragon who lives in the ocean that surrounds Midgard, the visible world. So enormous is he that his body forms a circle around the entirety of Midgard. He’s one of the three children of Loki.