Those who know about Norse Mythology know all about the Jörmungandr. Of course, those who play the God of War video games might also know of it too. Those games revolve around the Greek/Roman Gods in Mythology, so connecting Norse Mythology to things made sense. The versions you might read about differ depending on where it’s used.
You might also know it a bit from Marvel Comic books or films involving Thor, due to his connection in mythology to it. In Norse Mythology, the Jörmungandr (also known as the Midgard Serpent) is so long that he can wrap all the way around Earth or “Midgard.” He keeps his tail in his mouth, almost as a protecting shield. As the offspring of Loki and Andrboda, once the serpent releases its tail, “Ragnorok” begins. In Mythology, Thor battles and slays the serpent, dying in the process.