The Super Soldier Serum was a serum that was supposed to enhance a soldiers abilities. It was originally developed by Dr. Abraham Erskine to enhance all the physical and mental abilities to the pinnacle of human ability.
Erskine tested his serum on Steve Rogers, impressed with his want to serve in the war and his self-sacrificing bravery, who then underwent a successful transformation after the procedure from his sickly self to a taller and more muscular version. Johann Schmidt had intially supervised Erskine's initial work, and injected himself with an unfinished prototype of the serum. The prototype had the desired effect of making him physically superior, but burned much of his flesh away, leaving his face a disfigured red skull.
Years later, General Thaddeus Ross met with Dr. Bruce Banner regarding an experiment to make humans immune to gamma radiation. The experiment, which Ross hoped would restart Dr. Abraham Erskine's failed "super soldier" program, failed and exposed Banner to huge amounts of gamma radiation, transforming Banner into the Hulk whenever he became angry.
After being defeated by the Hulk, Emil Blonsky, a British Royal Marine tasked with leading a team to capture Banner, also agreed to treated by a "super soldier serum", but later he forced Dr. Samuel Sterns to inject him with Banner's blood, as he coveted the Hulk's power. Despite Sterns' warning that the combination of the super-soldier formula and Banner's blood may cause him to become an "abomination", Blonsky forced Sterns to administer the blood and a gamma charge. The experiment went wrong and Blonsky mutated into a creature with strength surpassing that of the Hulk.