Captain America: Dubbed unfit for traditional service, Steve Rogers became the first human trial of the Super-Soldier serum - the success of which boosted his strength, endurance and speed to the pinnacle of human achievement and led him to become Captain America!
Bucky: Born James Buchanan Barnes, Bucky was raised on base at Camp Lehigh where he befriended Pvt. Steve Rogers. Upon discovering Rogers was actually Captain America, Bucky became Cap's Sidekick in exchange for keeping his secret.
Golden Age Human Torch: A synthetic being able to create and control flames, the Human Torch aka Jim Hammond vowed to protect humanity and joined the Invaders during World War II. His legacy lives on in part thanks to Camp Hammond - the Initiative's training center.
Namor the Sub-Mariner: The child of an Atlantean princess and a human fisherman, Prince Namor spends time both above and below the waves. Endowed with incredible strength and the ability to fly, Namor was revealed to also be a mutant - explaining his winged feet!