The Midgard Serpent is a creature from norse mythology.
Jormungandr or as he is better known as the Midgard Serpent is the second child of Loki and the giantess Angerboda. When born it was assumed that the Midgard Serpent was the size of a human infant. When Odin realized him to be a threat to the gods he banished the serpent into the ocean depths of Midgard. Instead of maybe dying in the ocean, which may or may have not been Odin’s intentions, he survived and grew to an incredible size. When he finally came to full size he was big enough to circle the whole earth getting his name the Midgard Serpent. It was prophesied that he will bring death to most of the Asgardian Gods and that Odin's son Thor would be the one to kill him. It also continued saying that Thor will die by the serpent’s venom. The frost giants once challenged Thor to lift his cat from the ground with Thor tremendous effort he couldn’t lift the cat but he was only able to lit its paw up. Thor had felt foolish for not being able to lift it up but in reality the cat had been the Midgard Serpent in who used it magical ability of illusion to disguise and he had lifted one of its mighty hands which is like a seemingly impossible task lifting one of its immensely bulky arms in the air. Later thor learned that the cat had actually been the Midgard Serpent. He decided that he would try and stop the prophecy and kill the Midgard Serpent. Thor then went to the seas on a boat of the giant Hymir and used his enchanted line to fish out the Midgard Serpent. The serpent caught the line, the bait was an ox head, and Thor pulled Jormungandr out of the water. Hymir got scared and cut the line releasing the serpent Jomungandr back into the depths.
Loki and Tyr then stole all the golden apples which ensured the Asgards their longevity and concealed them to the Midgard Serpent. For the preparation of Loki and Tyr invasion of earth the Midgard Serpent in his ethereal form constricted the planets in his coils causing widespread storm, earthquakes, floods, and land slides. The serpent then used his body as a bridge from Asgard to Earth so that Loki and Tyr’s army could travel along his back. Thor then went on Hymirs boat again unto the sea of space outside of Asgard and confronted and battled the Midgard Serpent. The Midgard Serpent then said the battle was a stalemate and agreed to disgorge the golden apples that he had kept in his gullet. Thor then bound the Midgard Serpent to the roots of the world tree Yggdrasil. Loki turned against Tyr and Odin and his forces defeated Tyr and his army. In vengeance for her humiliating defeat to Thor hela cast a spell on Thor making him incapable of dying or healing injuries. When Thor found this out he created a suit of indestructible armor for him self. A band of frost giants went to earth to find the Midgard Serpent. They found him but in the form of Fin Fang Foom. Some time before Fin Fang Foom had been woken up from hibernation by dr.vault. Vault had taken over fooms mind. The dragon then fought It the Living Colossus until Fin Fang Foom got control again. Fing Fang Foom then broke off battle and swam back to his lair in china. The Midgard Serpent was please to comply with the giant’s requests once he heard of Thor curse. The Midgard Serpent did not intend on killing Thor but on wrecking so much havoc on his body that he’d be rendered helpless for ever. Then he could stop Thor prophecy of some day killing him. Jormungandr arrives in New York as Fin Fang Foom ad encountered Thor but due to Thors new armor neither of them recognized each other. They both then went to a deserted area to do battle where they revealed each other true identities to one another. A tremendous battle then took place ending with Thor using his full strength and entire power of the enchanted hammer mjolnir to deliver the finishing blow to the Midgard Serpent. The Midgard Serpent vanished upon his death presumably returning to his ethereal form. Thors hammer combined with the blow to the Midgard Serpent resulted in his body turning to into a gelatin like mass of flesh. Although he should have been dead due to the curse Thor still lived due to Hela’s curse. His spirit then went to the destroyer armor and forced Hela to resurrect him in his true body and fully restored health and to be free from her curse.
The Midgard Serpent was significantly much stronger than Thor, who had a strength level of over 100 tons at the time of their battle. He was also extremely long, able to coil around the Earth, and even during battle with Thor his whole body couldn't be shown. Jormungand also had the ability to cause floods, earthquakes, landslides, and many more, while making his body more solid. He was also virtually invulnerable to injury, as only a being like Thor could have caused him bodily harm. The Midgard Serpent could cast illusions, able to make himself look like Utgard-Loki's cat. He was apparently immortal, except for when he was killed by an extraordinary force (Thor). His venom was so potent that it could affect Asgardian Gods. Lastly, while in his solid form, it appeared that everything on Earth came to a standstill, even including birds in flight. However, this did not effect Asgard, Thor or any of the other nine worlds.