8. Steve Rogers (Captain America: The First Avenger)
Steve Rogers, the man who would become Captain America, was a sickly, skinny 90lb young man with asthma, who was repeatedly refused entry in to the army to help in World War II thanks to his build and poor physical health. Born in Brooklyn, New York, as a youngster Steve was attacked regularly by bullies in Hells Kitchen. However, Steve's resiliency, despite his small stature, inspires a young James Barnes to come to his aid and fight off the bullies, which results in them becoming friends. Even in to his adult life, he still finds himself on the end of regular beatings, but his continuous physical resiliency and toughness is a far cry from his wimpy physical appearance. Upon hearing how keen Steve is to join the army, Dr. Abraham Erskine - creator of the super-solider serum - finally allows Rogers to enlist. In his training period, he proves himself to be courageous and tough - far more so than men twice his size - even jumping on what he thinks is a live grenade to protect his fellow recruits. Ultimately, his heart and toughness is what prompts the army to make him the first super-soldier, giving him the physical appearance to go with his heart, after which he continues to prove how tough he is.