Godzilla (2010 Marvel Animated Universe)

Godzilla is a giant monster from Japan and an enemy of the Avengers. He appears in  Marvel's Godzilla vs the Avengers ,  Marvel's Godzilla vs the Squadron Supreme  and  Marvel's Godzilla: King of the Monsters.

Origin
Godzilla was a dinosaur that survived the extinction and gets mutated by nuclear radiation.

War against the Avengers
Godzilla has been sighted around the globe and attacks a nuclear power plant in Japan. He then swims towards New York to wreak havoc and battles the Avengers.