Midgard Serpent

The Midgard Serpent is a giant serpent from a jungle-like dimension presumed to be beneath Yggdrasil.

The Avengers: Earth's Mightiest Heroes
Loki was sent to the creature's dimension and was tortured by having venom dropped in his eye, possibly until the end of time.



Avengers Assemble (TV series)
After retrieving the Codgel, Doctor Doom with a little modification uses the weapon to release the Midgard Serpent with hopes of using it to conquer the entire globe. The creature is to powerful and would continue to grow until it consumes the Earth. After a battle with the Avengers, he and the creature are banished to the Realm Below using the extra-dimensional portal used by Ulik.