Red Skull was in charge of a Nazi group of terrorists called HYDRA. When he learned about Project Rebirth (The U.S. military project in charge of creating super solders such as Captain America), he attempted to copy the experiment, and became Red Skull.
The Red Skull was first seen leading his fellow villain allies, MODOK, Whiplash, and Venom into fighting several heroes (Iron Man, Spider-Man, Hulk, and Thor) until the heroes were accidently hit by Dr. Heinz Doofenshmirtz's powerful device called the "Power-Draininator." When Red Skull and his allies learn of Dr. Doofenshmirtz' device that drains the heroes' powers, they decide to seek him out, believing that his invention can be of good use for their own purposes. With help from Red Skull and the villains with him, Dr. Doofenshmirtz causes mayhem in Danville. Eventually, Doofenshmirtz reveals that his Power-Draininator was destroyed by his nemesis Agent Perry the Platypus after it drained the powers, much to Red Skull's anger; but Doofenshmritz manages to create a second and improved replica of the device, much to the Red Skull's delight. However, upon finally getting hold of the device, Red Skull betrays Doofenschmirtz by imprisonming him in a cage, believing him to have outlived his usefulness. It was then Red Skull reveals his true plans of using the Power-Drain-inator to destroy the Tri-State Area, before draining other superheroes of their powers so that he along with other villains can take over the world. Red Skull has MODOK to make several modifications to the Power-Drain-inator that will allow itself not only to drain any power from heroes, but also matter and living energy. With help from Phineas and Ferb, as well as from Perry, the heroes were able to regain their powers and defeat Red Skull and his villain allies, who are then arrested by S.H.I.E.L.D.
Red Skull has (as his name implies) a red skull shaped head. He also wears a navy green jacket with gloves as well.
Personality and traits
He is shown to look down on the heroes for protecting people. He is also a double crosser such as when he crossed Doof and locked him up because his period of usefulness had expired.
Red Skull is closely allied with fellow villains Whiplash, Venom, and MODOK. He was also briefly allied with Dr Heinz Doofenshmirtz, but betrayed him once he'd rebuilt the Power-Drain-inator.