Baron Zemo is a supervillain who first appeared in Marvel Comics The Avengers #4. His son, Baron Zemo the Second, first appeared in Marvel Comics Captain America #276.

When you're talking villainy, you're still hard pressed to beat a Nazi. When you're creating a villain that is responsible of putting Captain America on ice for a few decades, you have to go with a Nazi scientist who was creating ultimate vengeance weapons on the eve of Nazi Germany's defeat. That scientist would be Baron Heinrich Zemo. Founder of the Masters of Evil, the good Baron was consumed by his quest for revenge against Captain America. During one of his first run-ins with the Sentinel of Liberty, Zemo was trapped in his villainous mask, forever scarred by one of his own inventions, Adhesive X. Long after his father's death, Helmut Zemo would take up his father's quest, meeting a strangely familiar fate. Brilliant and dangerous, both father and son were consumed and scarred by their hatreds.

The greatest mind serves the greatest evil

Born into German aristocracy, Baron Heinrich Zemo was one of the greatest minds in the service of Nazi Germany. Living the good life, married happily to his love Hilda, mother to his loving son Helmut, Zemo was on top of the world. He used his formidable mind to further the German war effort, a firm believer in the Aryan cause. Working in hand with the likes of Arnim Zola and the Red Skull, Zemo worked to protect Germany from the Allied superhero team The Invaders, lead by Captain America.

Zemo's most notorious early invention was his hideous Death Ray which disintegrated its targets, living or inanimate. Sgt. Nick Fury and his squad of Howlin' Commandos were sent deep into enemy territory to destroy the superweapon. To keep the weapon from Allied hands, Zemo destroyed his own castle in an attempt on Fury's life. Threat destroyed, the Howlin' Commandos escaped. After the mission, word of the hideous weapon leaked to newspapers. Zemo was demonized, feared and hated even by the German people.

Fearing for his safety and the welfare of both his family and his work for the Fuhrer, Zemo slipped into hiding, working in secret and hiding his face under a magenta mask. Hitler was especially interested in Zemo's latest work, "Adhesive X", and he spared no expense in providing for the Baron. Adhesive X was a glue so strong that once applied, it was impossible to remove by any means. Envisioned as an offensive weapon capable of untold mayhem when used against Allied armies, the Baron worked feverishly on his invention.

Having been vilified across the free world, Zemo's profile as a target increased. Slaving away at perfecting his latest creation, Zemo was confronted by Captain America. In the ensuing battle, Captain America threw his shield at the only perfected sample of Adhesive X in existence to keep it from Nazi hands. Zemo was doused in his own invention before fleeing to safety. Celebrating his escape, Zemo attempted to remove his mask only to find it permanently bonded to his head. Unable to disrupt the bonds created by his own invention, Zemo was even forced to feed himself intravenously. This trauma drove Zemo insane.

Consumed by his hatred of Captain America, the Allies and anyone he felt was below his station in life, Zemo was a changed man. His idyllic family life was shattered and he began abusing his wife and child. Driven by his quest for revenge, he redoubled his fanatical devotion to his work, teaming with Arnim Zola to create powerful androids, a pistol sized death ray and other fantastic engines of destruction. No longer satisfied with simply inventing, Zemo turned to seeking out those he hated. Sabotage, espionage and terror became the Baron's life. During one of these missions, Zemo killed a costumed Polish freedom fighter called Citizen V. Germany's primary superpowered agent, the Red Skull, became increasingly aware of the rivalry for Hitler's attention Zemo represented. The two Nazi agents grew to hate each other as the competition grew.

In the closing days of World War II, both men knew Germany was on her knees. With Berlin under siege, the Red Skull hatched his last ditch plan for revenge against his nemesis Captain America. Ordering Zemo to London to capture an experimental drone plane from the Allies, the Red Skull plotted his own attack on Captain America. Sending Zemo to soften him up would buy valuable time for the Skull's preparations for a Fourth Reich. Zemo knew it was a fool's errand, but agree for another chance at killing the man who scarred him. To ensure a delay, the Skull leaked the details of Zemo's mission to Allied spies. If his rival was killed or captured, so much the better. Zemo made plans of his own. After taking care of Captain America, Zemo planned to fly to South America where he had prepared a secret base. Escape and revenge would be his.

As fate would have it, Captain America was already in Berlin when this plan was hatched. As Zemo prepared for his revenge, Cap confronted the Red Skull in their final wartime showdown. Learning of Zemo's mission, Cap and his sidekick Bucky raced back to London. Arriving moments after Zemo, the duo fell victim to a well planned ambush. Lashing the subdued heroes to the outside of the drone where they would die in the unprotected flight to Berlin, Zemo planned to show up the Red Skull by not only killing the heroes, but also delivering the useless drone to Germany as a final slap in the face to both the Skull and the Allies.

However, Zemo's plan was not without hitches. A team of Avengers from the future arrived via a time machine created by Dr. Doom to witness the event. The time machine rendered the heroes intangible to prevent them from ruining the timeline. As fate would have it, an accident allowed a future Captain America to secretly free his 1945 counterpart and his sidekick Bucky. Zemo adapted quickly to the situation. Discovering that the drone was, in fact, booby-trapped to prevent its theft, Zemo announced that it would serve the Third Reich well and launched it, knowing the heroes would try desperately to stop it. Captain America and Bucky raced after the drone on a motorcycle and leapt towards it. Cap couldn't reach it, but Bucky did. Warning Bucky to let go as he fell towards the icy Atlantic, Cap saw the bomb-loaded drone explode, killing his sidekick. Blasted deep into the freezing water, Captain America was thought killed. In reality the "Super-Soldier" serum in his body sent Cap into suspended animation for decades. The triumphant Zemo flew to his hidden South American base, abandoning his family.

Celebrating his revenge against the man who maimed him, Zemo set his sights on his new goal: a worldwide Fourth Reich with him in control. Zemo kept much of his youthful strength and vitality using Compound X, a life prolonging chemical of his own invention. Returning to science, Zemo developed the means to fulfill his new plan. Over the next few decades he worked on what would become his superweapon masterpiece: a gigantic satellite space mirror that would convert solar energy into a giant city destroying Death Ray. Zemo dreamed that ransoming countries into submission would be easy with that kind of power at his command.

An old foe, back from the dead

News of a revived Captain America soon reached Zemo. Raging that he was cheated of his revenge after all these years, Baron Zemo formed a new plan to kill him. Captain America joined a superhero team called the Avengers soon after his recovery from suspended animation. In order to counter Cap's new friends, Zemo formed the Masters of Evil. Recruiting the Black Knight, the Melter, and the Radioactive Man to help him deal with the Avengers, Zemo and the Masters of Evil attacked. Defeat soon followed. Adding the Enchantress and Executioner to the roster, and creating Wonder Man did little to improve the Master's luck. Even the help of the mighty Immortus did little to improve the results. Time and time again the group was beaten by the Avengers.

In what would be his final attempt on Captain America's life, Zemo had Cap's friend Rick Jones kidnapped and brought to his base. The Masters of Evil were sent to tie up the Avengers, leaving only Cap to save Jones. In the ensuing battle on a rocky mountainside, Zemo finally cornered his hated foe. Taking aim with his death ray, Zemo was blinded by sunlight that Cap reflected into his eyes with his shield. Stunned, Zemo fired wildly, causing a massive landslide that crushed him to death. But this was not the end of the Zemo threat...

The sins of the father

News of Heinrich Zemo's death unhinged his son Helmut. Abandoned by his father and left to fend for himself in war torn Europe, young Helmut Zemo and his mother suffered because of his father's infamy. Struggling to reclaim his aristocratic place is society, the arrogant and bitter Helmut strangely idolized his absent father. Hearing that Captain America was present at his father's demise made Zemo insane with rage. Vowing vengeance on the hero how had caused his family so much grief, Helmut followed in his father's footsteps, feverishly recreating many of his inventions and reclaiming his father's vast fortune. Obsessed with revenge, Helmut created a costumed identity called the Phoenix, and set his plans for killing Captain America into action.

Zemo's twisted mind planned the perfect revenge. The Adhesive X that scarred his father for life would be in the instrument of his foes destruction. Kidnapping both Captain America and his partner the Falcon, Zemo hung the duo above a vast boiling tank of Adhesive X, gloating about his victory and his revenge would finally be had. As heroes usually do, Cap escaped the deathtrap and fought Zemo to save the Falcon from certain death. Losing his grip on The Phoenix, Cap watched in horror as the young Zemo fell into the boiling vat, sinking out of sight, apparently to his death. The heroes left, assuming Zemo dead.

Surprisingly, Helmut survived the ordeal, but not without paying the price. Crawling from a pipe at the bottom of the vat, Zemo found that he had been horribly scarred by the scalding liquid. Hiding his face behind his father's trademark magenta mask, Helmut assumed the role of Baron Zemo. The vain Zemo was devastated by the horrible scars that covered his face. The incident cemented Zemo's hatred for Captain America as his only reason for living. Regrouping in Southern Mexico, and building a base like his father before him, Zemo plotted his next move.

Eventually joining forces with likes of Arnim Zola and the Red Skull, the young Zemo constantly tried to exact his revenge, but to no avail. Taking a more psychological approach than his father, Zemo tried to break Cap's mind rather than his body. From using old childhood friends as pawns against him to the mental torture of psychically reliving Bucky's death at the hands at the original Zemo, Cap endured all of Helmut's assaults. Even a new generation of The Masters of Evil got repeatedly thrashed by Cap's friends, The Avengers. Unfortunately for Helmut, his obsession had many of the same consequences as his father's. The rabidness of Zemo's madness helped him make many of his fellow supervillains his enemies. Retiring to obscurity to plan his revenge and fume at his failures, Zemo would hatch his most ambitious plot yet...

Justice Like Lightning?

When the supervillain Onslaught launched his massive assault on New York City, many of the Earth's superhero teams rushed to stop him. Seemingly killed in the final battle with the monstrous villain, the Avengers and the Fantastic Four were sucked into a pocket universe. To the world at large, the majority of the heroes that had protected them were lost, most likely dead. For out of nowhere, a new superhero team stepped up to fill the enormous power vacuum. The Thunderbolts quickly made a name for themselves in the post Avengers world. Adopted and loved by the citizens they fought to protect, few knew of the dark secret that the team hid.

Zemo had found himself without a purpose when Captain America seemed to meet his fate at the hands of Onslaught. Like his crafty father before him, he hatched a new plan. The public was desperate for heroes to protect them. Zemo knew that they would be easy marks for his deception. Gathering together many of his old Masters of Evil cronies and redressing them in new identities, Zemo created the Thunderbolts. By using his team to gather together a base of power, popularity and influence by opposing many of the villains he slighted when he was after Captain America, Zemo plotted his ultimate takeover of the world. As he suspected, the public was easily duped. Zemo himself adopted the persona of Citizen V, a costumed Polish freedom fighter his father had murdered during the war. The irony was not lost on the cruel Zemo.

During the months that the Thunderbolts lived and fought as heroes, they faced many of their former allies. Zemo was particularly incensed when they faced a new Masters of Evil lineup. Slowly, the Thunderbolts began to question their ultimate goal. Zemo himself began to soften, but never strayed far from his convictions. The leisurely pace of his plans would soon be ratcheted up.

The supposedly dead Avengers and Fantastic Four escaped from their imprisonment and returned to a jubilant public. Knowing his deception won't stand much scrutiny from the heroes they used to fight, Zemo began a desperate gambit. Exposing the Thunderbolts to SHIELD to ensure their loyalty to him, Zemo tried to seize power. Many of his own teammates turned against him and foiled his plan. Living the lives of heroes had changed them. His plot exposed, his team shattered and his nemesis back from the dead, Zemo escaped to plan his next move against the heroes of the Marvel Universe. Where and when he will return is not known, but his lifelong obsessions remain unfulfilled.