Mangog

Mangog, or "The Mangog" as it originally referred to itself, is the sum total of the hatred of a billion billion beings that were once killed by the ruler of Asgard and the Norse Gods, Odin. Imprisoned deep beneath Asgard, Mangog is accidentally freed by the Rock Troll Ulik, and goes on to wage war against Odin and the other Norse Gods on several occasions. Mangog proves to be physically unstoppable, and is usually only defeated by exploiting Mangog's dependence on psychic energies (such as hatred, fear, or feelings of devotion) felt by other sentient beings to sustain itself. Without such a source, Mangog shrinks to near nothingness.

While usually acting independently, Mangog also assists the Titan Thanos in a quest for universal domination, but is ultimately stopped by the Thunder God Thor. Thor eventually ends the threat of Mangog entirely: having inherited the Odin Force, Thor simply dissolves an attacking Mangog with a wave of his hand.

Months, perhaps even years later, amoral business-man (and possibly demi-god) Adam Mann constructs the Mysticator, a magical generator which taps into an otherdimensional source of energy to give him immense power. When the generator is overloaded by the mace of Thunderstrike, however, it is revealed the source of its energy is actually the Mangog, which breeches through to Earth to renew his battle with Thor. Thor demands to know how it is possible that the Mangog lives again, and the monster proclaims that he can never be ultimately destroyed - he is living hatred, he feeds on it and grows, and will endure as long as hate exists.

The Mangog was banished, this time tumbling into a star, but if his claim has any merit, he will always eventually return to plague the universe and Thor in particular.

Trivia

 * If Mangog truly is an embodiment of hatred he would be an agent or alternate form of Master Hate, the supreme entity of hate in Marvel comic - this would explain his ability to defy almost any force as well as his dependency on negative emotions.