The Avengers are Earth's Mightiest Heroes, so they often face down Earth's mightiest threats. Whether it be Ultron trying to destroy humanity, Doctor Doom getting up to mischief, or the Red Skull and Hydra mobilizing, the Avengers are there for all of it. They are also there for the threats that aren't as well known, too. These B-list villains are no less powerful or deadly than the big names, just not as famous.
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