Mangog

"With the boiling hatred of a billion billion souls, we live again! By Odin's foul treachery we were imprisoned. But now to vengeance! To Asgard! Odin! We come for you!"

- Mangog

Mangog was a powerful being composed of the sum total of the hatred of a billion billion beings that were once killed by the ruler of Asgard and the Norse God, Odin.

Biography
Mangog was a powerful creature of pure rage that was created by Odin centuries ago. Over time however, the creature developed a growing hatred for Odin and eventually became a grave threat. Seeing that the creature was too dangerous, Odin locked the creature away in Niflheim; where it rested for years and years until accidentlly being set free by Odin's son Thor. Thirsty for revenge, Mangog fled to Asgard to defeat Odin, who was now regenerating his powers in his Odinsleep. Eventually however, Odin awakened, and teamed up with his son Thor and his adopted son Loki to defeat the creature once and for all.

Odin then released all the souls trapped in Mangog and allowed them to rest in peace.

Trivia

 * Mangog was planned to be one of the villains of Thor: The Dark World but the idea was later rejected.