The character first appeared in Tales to Astonish #62, and was created by Stan Lee and Steve Ditko.
Born Samuel Sterns in Boise, Idaho, he worked for a chemical plant in a menial capacity. While moving radioactive materials into an underground storage area, some of the radioactive materials explode, bombarding Sterns with gamma radiation. He recovers, and finds that the radiation has changed him from an ordinary human into a green-skinned, super-intelligent entity with an oversized brain housed in a towering cranium. As is the case with most individuals mutated by gamma radiation early-on, the particular set of characteristics Sterns acquired by exposure to it were said to result from a subconscious desire; in his case, the desire to be as smart as his brother Philip, who was a physicist in the employ of the same facility. Calling himself the Leader, Sterns embarks on various ambitious criminal schemes, with the Hulk as his primary nemesis, consistently backed by a self-constructed army of super-strong, virtually invulnerable plastic Humanoids.
The Leader creates a spy ring to overthrow the United States federal government. He sends a spy to steal a robot Dr. Bruce Banner was developing. The spy is knocked into a deep pit by the Hulk, and is trapped there. The Leader dispatches the Chameleon to find out why the spy has failed to report back. Although the Chameleon fails at this, he informs the Leader of the secret shipment of a newly developed nuclear device, the Absorbatron. The Leader sends a Humanoid to steal the device. The Humanoid is stopped by the Hulk, who the Leader sees for the first time through his Humanoid's eyes. He deduces that the Hulk is a creation of gamma radiation like himself, and becomes immediately obsessed with learning more about him. Thus, though he sends out a horde of Humanoids to seize the Absorbatron while it is being tested on a deserted island, when the Hulk is sighted there he focuses on capturing him instead, now convinced that the two of them are "fated to become allies". However, the Hulk is unwittingly saved from capture by US army troops. A third attempt at stealing the Absorbatron is successful, and the Hulk is delivered into the Leader's hands at the same time. However, while the Leader is still scientifically studying him, the Hulk breaks free and proves impossible to reason with. He destroys the Absorbatron, and the Leader narrowly escapes with his life. In order to sell his 500-foot (150 m)-tall Humanoid to hostile nations, the Leader arranges a demonstration of its power by ordering it to attack a nearby missile base. However, the army hits the Humanoid with a "Sunday Punch" missile, rendering it inoperative. When the army subsequently corners the Hulk in a cave, the Leader rescues him, and the two become uneasy allies. The Leader operates on the Hulk to remove what would have been a fatal bullet in his skull, and further enhances his strength with a shower of gamma rays. The two of them team up to steal the Watcher's "Ultimate Machine", a device containing all the knowledge in the universe. Rather than stop them directly, the Watcher implants within the device an image so horrifying that using it causes the Leader to collapse dead from sheer terror. However, the Leader had made preparations even for his death; a special humanoid is programmed to activate when his heart stops beating, and carry the Leader to a "Revivor Beam" which would restore him, since his gamma-infused body takes longer to reach brain death than that of a normal person. In addition, his usage of the Ultimate Machine apparently unlocked several previously latent mental powers.
After months in hiding, the Leader offers General Ross aid in neutralizing the Hulk, containing him within a cage of plastithene. However, Betty Ross overhears the Leader gloating to himself about his real plan: to take over the base and use its nuclear missiles to set off a nuclear war, thus annihilating most of humanity and making it easy for him to take over. She frees the Hulk, who stops the Leader's plan. However, the Leader escapes and uses his powers to erase all memory of his scheme from the base's inhabitants except Ross. The Leader hijacks the U.S. Army's Murder Module vehicle, but it is then destroyed by the Hulk. As revenge, he interrupts the wedding of Banner (the Hulk's alter ego) and Ross by shooting Banner with a ray which turns him into an unusually savage form of the Hulk. After briefly turning back into Samuel Sterns to question Banner about the Hulk's possible weaknesses, he resurrects the Glob and brainwashes him into attacking the Hulk. The Leader next tries petitioning General Ross and Major Glenn Talbot to let him use the U.S. Army's Brain-Wave Booster, a mental amplifier so powerful that no normal human can use it. In a retcon of his earlier mind-wipe, Ross and Talbot remember the Leader's attempt to set off nuclear Armageddon, but they trust him to use the device responsibly anyway. He briefly uses the device to beset the Hulk with three-dimensional projects of his enemies, but the Brain-Wave Booster proves too advanced for even the Leader's brain, and it causes him to suffer a mental breakdown. The Leader then creates android duplicates of the President, Vice President, and military personnel in an attempt to kidnap the real President and Vice President. He then superimposed his consciousness upon the Rhino in order to battle the Hulk. He later used the Hulk and the Thing as pawns in a contest with Kurrgo.
Some time later, the Leader briefly took over Gamma Base. Some time after that, he gamma-irradiated Manhattan's water supply in an attempt to mutate humanity like himself. He later activated Arsenal, and then dispatched the Avengers through time.
After a period of time, the gamma radiation in his body began to wear off. At first, the Leader attributed his lapses in concentration to overworking his mind finding ways to defeat his greatest enemy (the Hulk). By the time the Leader realized what was happening, much of the intelligence that could have solved his plight was gone and texts that were once child's play to him were now hopelessly beyond him (he even forgot the access code of his secret base). In this period, he made cash however he could by means fair or foul, until he managed to convince the Gray Hulk to help him regain his intelligence by promising that he would help the latter to remain the Hulk full-time (instead of only at night).
Rick Jones had been afflicted with a Hulk-like condition and the Hulk (using Bruce Banner's memories of gamma transfer) devised a machine to transfer all of the gamma radiation from Rick Jones to the Leader. However, this time the mutagenic process was slightly different resulting in a cranium that resembled an oversized brain, rather than a towering forehead. He was also a lighter shade of green. As a side note, this transfer also created a psychic link between the two.
Soon after this, the Leader would steal the seemingly lifeless body of General Thunderbolt Ross from the back of an ambulance, simply because it was there, and later managed to revive it as a mindless vegetable, which he used as an armored enforcer.
Before long, the Leader's new form was revealed, and he dispatched Half-Life to battle the Hulk. The Leader dispatched an army of four-armed robots against the Hulk, and created Rock and Redeemer.
The Leader dispatched Rock and Redeemer against the Hulk. Following this the Leader engaged in a scheme to detonate a gamma-bomb in a small-town city, Middletown, Arizona, killing over 5,000 people, and the few, now enhanced, survivors provided him with valuable research subjects and superhuman enforcers called the Riot Squad. With their help, he built a self-sufficient society called Freehold in the Arctic, populated with civilians dying from radiation poisoning. Some time afterward he gave the Hulk information how to find his brother, Philip Sterns, the Madman, since he thought it would be best to put the latter out of his suffering, due to his original personality being slowly and painfully eaten away by the Madman persona.
After Jones suffered a great mental trauma due to the death of his girlfriend Marlo Chandler, his pain was enough to cause the Leader considerable discomfort, motivating him to work towards the revival of Marlo. At this time Freehold was targeted by a rogue branch of HYDRA terrorists, employing the U-Foes and his followers to invade the covert Pantheon organization, of which Hulk was a member, to coerce them to help him in defending it. He employed something he ironically called the Deus Ex Machina in conjunction with his follower, the gamma-enhanced reverend nicknamed Soul Man, who falsely believed himself to have been blessed by God with spiritual power, rather than given nearly godlike abilities by the Leader, in an effort to revive Marlo and siphon off Soul Man's power for himself. Rick Jones became convinced to accept the help after seeing the mindless, but mobile, body of Thunderbolt Ross.
The Hulk, manipulated by the leader of the Pantheon, Agamemnon, attacked the facility. At the same time, HYDRA decided to storm the base, leading to a multi-sided battle. The Hulk eventually personally attacked the Leader, who, along with Soul Man, seemingly perished in the crossfire. The machine was likewise demolished, causing Marlo to enter a state similar to Ross, but both eventually fully recovered.
The death of the Leader left his follower Omnibus in control of Freehold. Omnibus used mind-control to manipulate several U.S. chiefs of staff, and engineered many high-profile terrorist strikes to incite global warfare, as he reasoned that it was inevitable, and hurrying it along offered him opportunity to enable his personal society to survive and inherit the Earth. Omnibus was eventually exposed by his fellow Freehold citizens, judged to die in the cold, and was eaten by a polar bear. Bruce Banner also saw the Leader in a supposed trip to Hell.
A while later, the Hulk, who in his Bruce Banner persona was suffering from a degenerative nervous condition (which would ultimately kill him) was confronted by the Leader once again. Apparently he really had perished when the Deus Ex Machina was destroyed, but his disembodied consciousness had evolved beyond the need for a body. Although he was in the process of building a new body out of random organic materials, in a secluded cave near Gamma Base, he was preparing to leave this level of reality behind altogether, transcending both beyond the physical and his old goals. Yet before he did so, he intended to cure Bruce Banner for reasons all his own. After he had done so, he abandoned his body. However, later still his consciousness once again contacted Banner, apparently shocked by what he had discovered "beyond the veil"; he was unable to return, however, and was not heard from again until much later.
During a time of great personal duress for the Hulk and Bruce Banner, who had begun to merge their personas, it became clear that Home Base, a secret organization who had relentlessly pursued the Hulk in order to obtain his genetic material, was secretly led by the Leader. In the end, after all his other agendas had failed, the Leader finally managed to mind-control the Hulk and guided him towards his secret base, with the intention of taking his indestructible body for himself. Because of intervention by Nadia Blonsky, Betty Ross, Doc Samson, and Iron Man, the plan failed and the Leader died again.
These events, bizarre and nebulous as they seem, may or may not have taken place in this form... they may be partly true, or entirely a construct by the extra-dimensional demon Nightmare in a bid to avenge himself on the Hulk. At present, the Leader has a body incorporating traits from both his previous incarnations; it is unknown exactly how he acquired it, but it may have been relatively easy, given his history.
The Leader is captured by S.H.I.E.L.D.'s Hulkbusters, and brought to trial for his crimes. He was represented by Attorney Mallory Book from She-Hulk's firm Goodman, Lieber, Kurtzberg & Holliway. During the trial, Ms. Book argued that the Leader was not responsible for his actions since the Gamma exposure forcibly changed his personality. To prove her point, Book compared She-Hulk to Jennifer Walters, revealing that Jennifer was much more promiscuous in her She-Hulk form. In the second day of the trial, Leader's humanoid droids arrived to rescue him. Instead of escaping, the Leader called off the attack, opting to see the trial to its conclusion, as he correctly predicted that his defense was going to win. He was found not guilty. It is as yet unclear whether this person is indeed the original Leader, or the Samuel Sterns of "Earth-Alpha", the inhabitants of which had been swapping places with their 616 counterparts for a while prior to this trial.
Now a free man (whichever one he may be), the Leader teleported the Hulk's allies, the Warbound, to Nevada. There, he used Hiroim of the Warbound, harnessing his tectonic power to activate a gamma powered shield over a portion of the desert. It is revealed that the Leader is dying, and that he constructed the dome to cure him. Due to a miscalculation, the energy of the dome actually kills him faster. In battle with the Warbound, the Leader is stabbed through the chest with an iron pipe. The Leader then absorbed the power of the dome, turning himself into a gray-skinned giant. Hiroim also absorbed the power, and battled the Leader, draining both of their powers. In death, Hiroim channels his old power into Kate Waynseboro, who attacks the Leader, and forces him to teleport away.
The Leader, apparently healthy and in the form he originally had, appears once again, this time with designs on the Hulk's son Skaar. It is eventually revealed that he, along with a select group of genius super-villains, is part of a longtime collaboration he calls The Intelligencia. Leader was also responsible for mutating Marlo Chandler into the new Harpy. During that time, he planned revenge on Kate Waynesboro.
At the conclusion of the Red Hulk storyline, a newly rejuvenated Red Hulk approaches the Leader and gets close enough to him to completely drain the body-altering gamma radiation from the Leader's physiology. Red Hulk does this as a punishment for the Leader's altering of Ross's/Red Hulk's daughter into the Red She-Hulk. Red Hulk leaves Sterns alive to suffer, reminding him that as the person he has been reverted to with his original, well below average intelligence, Sterns will never be able to duplicate a gamma-infusion and return his powers as The Leader... at least not on his own.
A powerless Leader is later seen in custody demanding "gamma" (the one thing no one is willing to give him) if he was to divulge any information on stopping the Intelligencia's failsafe doomsday plans.
At the end of the second issue of the new Thunderbolts series as part of the Marvel NOW! event, a powerless Samuel Sterns is seen apparently housed within a shipping container. His head is connected to a machine apparently emitting red gamma radiation (in the fashion of the Red Hulk) with the harness in the shape of the Leader's formerly tall head. Samuel Sterns is apparently in the custody of Red Hulk. During the third issue, Samuel Sterns has reddish hued skin, but with no apparent powers. Once Deadpool sees that the Red Hulk is employing Samuel Sterns, he expresses his view that the Punisher will not be pleased. As soon as the Punisher sees Samuel Sterns, he shoots him right between the eyes, killing him and the Red Hulk's plan. During the fight against Madman, Red Hulk took him to a pipe line that feeds Gamma energy to Madman's lab. Red Hulk then absorbed the energy himself and then force fed it to the Leader, bringing him back to life. Leader then joins the Thunderbolts under the new alias Red Leader. Leader then realized that his brother, Madman, tricked him into divulging where he hid his second brain and the algorithm hiding—it was on the internet. After gaining back his memory and intellect he then whispers something into his brother's ears that causes him to die.
Leader then tricks the Thunderbolts into taking names out of a hat to decide whose mission will be next. He picks the name, since he has "no skin in the game", and chooses Punisher, since he knows he will want to go to New York City. He hopes to escape Ross, but the Infinity crossover occurs and he is forced to release Mercy when Supergiant of Thanos' Black Order sucks part of his intellect. He then helps Red Hulk destroy The Black Orders flagship, but only for self-preservation. He constantly broods over how he should kill the rest of the Thunderbolts.
Later the team is teleported to Hell and Leader then negotiates a contract with Mephisto that if Ghost Rider and Red Hulk defeat the current leader of hell, Strong Guy, they will be teleported out and Mephisto will take control of Mercy, as well as other secret stipulations.
Leader then helps the team navigate the haunted swamps of Honduras since he can translate an ancient map. During the boat ride he whispers something in an ancient language that causes Ghost Rider to lose his powers and get devoured by a tentacled monster. Their river guide then makes a deal with Leader to betray his team, but leader double crosses him and the team kills the guide's ambush. Leader then tells the team to enter the temple, but via a booby-trapped path that gets them all killed, except for Ross, who finds the source of the temples power—an infant Celestial's head. Leader is killed when his head explodes after drinking the Celestials' blood. He and the team are revived when Ross makes a deal with a Celestial powered being and teleports them back to before the mission started.
After Punisher quit the team, Red Leader, long looking for ways to kill the Thunderbolts and knowing Castle had counter measures to take each of them down, put a bomb in his safe house with a note "You don't quit us. You're fired" knowing he would survive and he would think it was Ross who attempted to kill him, and would take the Thunderbolts down.
Six months after the Thunderbolts disbanded, the Red Leader had built his own criminal empire in Kata Jaya. Living a life of luxury and trying to conquer the heart of the girl he was in love with, Red Leader saw everything he had built be destroyed by his former partners and the Avengers. Betrayed by Caitlin (the girl he loved), Red Leader was captured by them and put on a jail. Punisher used the Ghost Rider's skull to put Sterns under permanent Penance Stare, but he was eventually freed from it by Mephisto (with whom he had made a deal when he went to Hell along with the Thunderbolts). Enraged by the fact that Red Leader had reneged their deal, Mephisto made him sign a new contract and led him to Hell.
As part of his measure to neutralize Gamma mutates across the world, Hulk's Doc Green form pinned down the Red Leader who through unknown means escaped from Hell and had started to play with occultism and neutralized his Gamma-powered abilities. However, Red Leader had been reached out previously by Gammon (an artificial intelligence duplicate of Doc Green) who had implemented a countermeasure against Doc Green's actions. As soon as he was depowered, Red Leader slowly transformed back. Instead of transforming back into Samuel Sterns, Red Leader regressed back to Leader. He and Gammon agreed to work together.
The Leader has superhuman mental acumen, as a result of his exposure to an explosion of gamma-irradiated waste. He possesses enhanced intuition, pattern solving, information storage and retrieval, and logical and philosophical structuring. His ability to predict probable outcomes of tactical and strategic scenarios is so advanced that it borders on clairvoyance. The Leader has a perfect memory with the ability to recall every moment since the accident that gave him his powers. In addition to his superhuman intelligence, the Leader has limited but potent telekinetic and telepathic powers. He is able to mentally control non-gamma-mutated individuals upon touching them, and has toppled a very weakened Hulk with his telekinetic blasts.
The Leader possesses knowledge of genetics, physics, and robotics, and has designed a large number of sophisticated weapons, vehicles, computers, androids, and synthetic humanoids. He is particularly adept at genetic engineering and manipulating radiation for various nefarious purposes.
On occasion, the Leader showed the ability to turn himself back into Samuel Sterns, but this ability resulted in him losing all memory of his identity as the Leader as Sterns's mind was ill-equipped to cope with the Leader's intellect (although he always remembered everything when he turned back into the Leader again).
Prior to the release of The Avengers in 2012, Marvel ran a series of canon tie in comics entitled "Avengers Prelude: Fury's Big Week", which take place within the Marvel Cinematic Universe. In issues 6 and 7, Sterns is seen undergoing a rapid head mutation just as he is discovered by Natasha Romanoff who stumbles upon him immediately after Hulk has escaped. Although his brainpower has already drastically increased to the point where he can pinpoint the exact location of Black Widow's birth just by a brief hint of Stalingrad in her accent, Natasha shoots him in the leg when he attempts to bribe her by offering to help her return to her home and he is detained into S.H.I.E.L.D. custody.
The Leader makes an appearance as a zombie in Marvel Zombies vs. The Army of Darkness in the horde that overwhelms and infects the Punisher. He has a giant hole blown through his cranium which does not stop him. He is also in Marvel Zombies 3 where he is looking over food and medical supplies that other zombies have found as an offering to a zombie Kingpin. The Leader determines how long the others can feed on the human clones. The Leader is sent with other zombified superbeings to find and destroy the Machine Man. The android gains the upper hand in the battle and destroys all his pursuers. The Zombie Leader then kills himself by ripping out his arm, using it to take out all of his brain, and ripping out his own body.
The Ultimate version of Leader made his first appearance in Ultimate Human #1, a miniseries starring Ultimate Iron Man and Ultimate Hulk. This Leader is also the Ultimate version of MI6 agent Pete Wisdom. In the Ultimate universe, Wisdom is an ex-British Intelligence agent thrown out of the organization after testing his "British Enhancile Program" on himself, transforming him into The Leader. Wisdom has psychic and mental abilities similar to the original Leader, but requires a wheelchair and a halo brace to support the weight of his enlarged cranium. The Leader attempts to steal Tony Stark's nanotechnology as Banner and Stark work together to try to incorporate it into Banner's physiology in the hopes that it will grant him control over his transformations into the Hulk. When Stark commands a decoy Iron-Tech robot into the base of the Leader, Banner transforms into the Hulk. The Hulk resists the Leader's influence, and pounds him into the ground. The Leader, almost dead, commands a C-17 down onto the Hulk, ultimately killing Wisdom/Leader.
In Ultimate Mystery an elderly Dr. Samuel Sterns (who is seen in a wheelchair) is amongst a group of younger versions of Earth-616 villains and heroes including Doctor Octopus, Arnim Zola III, Misty Knight, Nathaniel Essex, and Dr. Layla Miller. They represent a brain trust for Roxxon Industries. He is later transformed into a Hulk/Leader hybrid where he attacks Spider-Man, but is defeated.The Leader appears in "The Incredible Hulk" portion from the 1966 The Marvel Super Heroes, voiced by Gillie Fenwick.
The Leader appears in the 1980s The Incredible Hulk episode "Punks on Wheels", voiced by Stan Jones.
The Leader appears as a villain in the Iron Man episode "Hulkbuster", voiced by Matt Frewer.
The Leader is featured as a recurring villain in the 1990s UPN Incredible Hulk series, with Matt Frewer reprising his role. He is served by Gargoyle, Abomination, Ogress, and the Gamma Warriors (who were created from Hulk's DNA).
The Leader cameos in The Super Hero Squad Show episode "Tremble at the Might of MODOK". He is shown at a convention of evil geniuses.
The Leader appears in The Avengers: Earth's Mightiest Heroes episodes "Hulk vs. the World", "The Breakout: Part 1" "Gamma World", and "Assault on Prison 42", voiced by Jeffrey Combs. In "Hulk vs. the World", Leader is shown as an inmate of the Cube.
The Leader appears in Hulk and the Agents of S.M.A.S.H., voiced by James Arnold Taylor. He is a recurring enemy of the Agents of S.M.A.S.H. and holds the key to Skaar's past.
The Leader appears in the Ultimate Spider-Man episode "Contest of Champions" Pt. 3, voiced again by James Arnold Taylor. His mind and MODOK's mind end up attacking Spider-Man, Iron Spider, and Agent Venom. Upon agreeing to free them, Spider-Man wants them to work the teleporter machine to get all the civilian hostages back to Earth. Leader and MODOK work the teleporter while the others fought Grandmaster. As the final civilians are being evacuated, Leader and MODOK took the opportunity to get teleported out of the Grandmaster's ship.
The Leader appears in the Avengers: Ultron Revolution episode "Building the Perfect Weapon," voiced again by James Arnold Taylor. He works on his plans to make the perfect weapon by stealing A.I.M. technology. When the Avengers and Red Hulk show up, Leader unleashes Ultimo on them while he gets away. When at an offshore island, Leader makes it so that Red Hulk got by the traps that the Avengers have a hard time getting through. Leader lures Red Hulk into a room that contained a particle-accelerator gamma bomb which he will use on Red Hulk. After Red Hulk fails to disarm the bomb and is caught in the explosion, Leader appears before the Avengers stating that he created the perfect weapon as an enlarged Red Hulk appears near him. In the episode "World War Hulk," Leader loses control of Red Hulk and is beaten into a state of unconsciousness.
Dr. Samuel Sterns appears in the film The Incredible Hulk, portrayed by Tim Blake Nelson. In this film, he is a university professor trying to help Bruce Banner find a cure for his transformations, while operating under the alias of "Mr. Blue". After turning Emil Blonsky into the Abomination, some of Hulk's blood drips into an open head wound causing his cranium to rapidly expand as he grins maniacally.
The Leader appears in the Hulk video game (which picks up after the film of the same name), voiced by Michael Dobson. In this game, he plans to create a gamma mutant army to take over the world using a special "Gamma Orb", with help from his brother Madman, and fellow enemies of the Hulk such as Ravage and Halflife. He moves with teleportation, and battles the Hulk with mental abilities of levitation, energy manipulation, and creating illusions of himself.
The Leader appears as a playable character in Lego Marvel Super Heroes.
The Leader appears as a playable character in Lego Marvel's Avengers.
Dr. Sterns appears in The Incredible Hulk video game, with Tim Blake Nelson reprising his role from the film.
The Leader appears in Lego Marvel Super Heroes, voiced by Jeffrey Combs. He is shown as an inmate at the Raft and is defeated by the superheroes.
The Leader appears as a villain in Marvel: Avengers Alliance, making his debut in Spec Ops 32 in which he kidnapped Betty Ross and turned her into the Red She-Hulk. He was defeated by the Red Hulk but out of rage injected him with the same serum he used on Betty transforming him into a more powerful version of himself now known as the Red Leader.