Johann Schmidt is the leader of Hydra, a terrorist group derived from the Nazis. He was powered by an early and unstable version of the Super-Soldier Serum, and adopted the identity of RedSkull.
Since then, he has battled Captain America and his fellow heroes for years, without ever achieve his goals of global domination.
The Avengers Protocol, Part 1
Dying from his failing Super-Soldier Serum, Red Skull asked help from M.O.D.O.C. in order to transfer his mind into Captain America's body, so he could retain his powers since the serum successfully bonded with that body without it killing him.
Red Skull had a bunch of Hydra minions attack Captain America, he managed to imprison and teleport him, but was attacked by Iron Man who thought he witnessed Cap's death. He subsequently reassembled the Avengers and attacked the Hydra base with great haste. Red Skull had managed to take place in Cap's body, but the process was inverted, only for M.O.D.O.C. to rip the Iron Man Armor and the Arc Reactor from Tony Stark and transfer them to Red Skull, who then dubbs himself the Iron Skull. The two villains then are forced to retreat, with Stark left for dead.
The Avengers Protocol, Part 2
In order to achieve his dream of world domination and victory over the Avengers, Iron Skull wanted to destroy their members, resources and ultimately public image. He infiltrated the Avengers Mansion where he planted a bomb on the mansion reactor, and infected the Avengers with microbots sending aggressiveness stimulation's, making them battle each others in front of the civilians and media. Stark managed to nullify the microbots actions using concentrated EMP beams, and rallied the team around his lead to defeat and force to retreat Iron Skull.
Angered by his failure, Skull called to the Avengers' old foes, Doctor Doom, Dracula and Attuma, to join him in his Cabal, as an evil counterpart to the Avengers. Those communications were also caught by Stark and his teammates, who were now perfectly aware that Skull would seek for revenge.
The Serpent of Doom
The Iron Skull tries to contact Doctor Doom again to recruit him to his Cabal but Doom once again refuses, which led Doom to be an enemy of the Cabal, as a result.
Red Skull contacts Dracula telling him of the properties of the Super-Soldier Serum which leads to a fight with the Avengers. In his defeat the Skull visits him at Castle Dracula and offered him a position in the Cabal.
Hyperion and Attuma
The rest of the Cabal finally forms, with Attuma deciding joining them. They tried to destroy the Avengers, by using their own battle methods against them. They failed, but succeeded at one part of their plans to rescue Hyperion from S.H.I.E.L.D., and have him join the Cabal. Together, they attempted to kill Doom and steal the Tesseract, as of which they succeeded partially as they had retrieved the Cosmic Cube.
Betrayal and brief career as the Cosmic Skull
The Skull with the Cosmic Cube in his possession was planing to rule all dimensions, but ended up betraying the Cabal and being humiliated by the Avengers. He briefly became the Cosmic Skull, but due to M.O.D.O.C., the rest of the Cabal and Tony, he was seperated from the Cosmic Cube and was then flung into another dimension, where he met his true boss, Thanos.
Escape from Thanos
The Red Skull betrayed Thanos and was able to escape back to Earth. Unfortunately, he was followed by Thanos' droids, and ultimately crashed in Brazil. The Avengers investigated the scene, and found a mentally-unbalanced Red Skull with a Infinity Stone, which he had stolen from the Mad Titan. He was then imprisoned by the Avengers to get more information about Thanos to little to no avail. When Black Widow and Hawkeye interrogated him, his only response to them was that "He would rise".
The Avengers used the carvings that the Red Skull made in his cell to locate another one of the Infinity Stones, the Time Stone. The arrival of said stone create temporal anomalies, like the appearance of dinosaurs, robots from the future, or Hydra battalions from WWII which wrecked havoc in Manhattan. In the middle of the chaos, the Red Skull escaped his cell, and tried to get the Time Stone, which had been attached to Tony Stark's arc reactor, and caused him to continually de-age to the point of being a child.
Once the Red Skull got hold of a kid Tony Stark, a pulse from the Time Stone barely de-aged the Red Skull and reverting his mind to a normal state. Captain America fought the Red Skull to save Tony, who soon managed to put on an adjusted Iron Man armor for his young body. Tony attacked the Red Skull with a repulsor ray which blasted the villain out of the tower. Red Skull was then caught by one of the pterodactyls which had been brought to the present by the stone, defeating him, but ultimately ruining their chances of getting information on how to stop Thanos.
Powers and Abilities
Superhuman strength, reflexes, stamina, agility, and a hyper-accelerated healing factor on a similar level to Captain America. He also seems to no longer age since he was injected with the serum that gave him his powers.
Formerly when fused with the Cosmic Cube, dubbed the Cosmic Skull he had many God-like powers like flight, near invulnerability, even faster healing, enhanced strength, speed, reflexes, cosmic energy manipulation, projection and teleportation
Genius level intelligence and a skilled leader
Supersoldier serum the Red Skull took was inperfect and it weakened him after decades. But after bonding with the tesseract & tesseract instantly "healed" his super soldier serum
He's very arrogant and often underestimates his enemies and his social abilities in making aliances are fairly limited.
Formerly the Red Skull had became insane after working with Thanos, he was also reliant on stolen one of Iron Man Armor's to maintain life.