Colossus

Real Name:  Peotr Rasputen

Colossus is a member of the X-Men, and may convert his body into organic steel, giving him extraordinary strength and durability.   

Colossus has not appeared in any episodes of the Avengers: Earth's Mightiest Heroes, but was confirmed as existing in the continuity by being one of the heroes the Super-Skrulls were able to replicate.