Baron Zemo has returned to the MCU in the Disney series The Falcon and the Winter Soldier. His first appearance in the Marvel Cinematic Universe was in Captain America: Civil War, but he was nothing like his comic book counterpart. In the movies, Zemo was simply a man seeking vengeance when the war against Ultron destroyed Sokiva and cost him the lives of his family.
However, in Marvel Comics, Helmut Zemo is the son of one of Hydra's most villainous leaders. Created by Roy Thomas, Tony Isabella and Sal Buscema in 1973's Captain America #168, the younger Zemo carried on his father's penchant for destruction and world domination into the new era. After failing on numerous occasions with his Masters of Evil, Zemo came up with a great plan when he turned his group of villains into a team of heroes called the Thunderbolts. Despite his intentions, that team morphed into a central part of the Marvel Universe that surpassed anything Zemo could have fathomed that left him far behind in the dust.
The Thunderbolts' first appearance was in 1996's Incredible Hulk #449 by Peter David and Mike Deodato Jr. A superpowered team attacks the Hulk and reveals themselves to be the Thunderbolts. This team included Mach-1 (Beetle), Meteorite (Moonstone), Atlas, Techno, and Songbird. However, Hulk surrendered and waited for the leader, Citizen V, to show up. Although he appeared in a costume that had the red, white, and blue of the U.S. flag on it, the man under the mask was Baron Zemo and the heroes of this team were really the Masters of Evil.
Baron Zemo created the team to take down his main nemesis, Captain America. However, the Sentinel of Liberty, along with the Avengers and the Fantastic Four, all seemed to perish in their battle with Onslaught. In light of this, Zemo started to paint the team as heroes, with the Baron hoping to use the goodwill they were building to get access to S.H.I.E.L.D. and Avengers' files and use them for personal gain and profit by selling the data to the criminal underworld. However, the Thunderbolts enjoyed working as heroes, and when the teenaged Jolt joined them, the team embraced their new roles even more.
Baron Zemo then made a huge mistake. In Thunderbolts #10, by Kurt Busiek and Mark Bagley, Zemo decided he would force the Thunderbolts to return to their evil ways by outing them to the public, revealing their identities to everyone through a setup with S.H.I.E.L.D. Just like that, the newest heroes were now hated by everyone. When the Thunderbolts refused to follow him any longer, Zemo ended up mind-controlling The Avengers and Fantastic Four and sent them after the team of former villains. Luckily, Iron Man remained unaffected and helped the Thunderbolts defeat Zemo.
With Baron Zemo gone, it was time for the Thunderbolts to regroup and figure out their next steps. The team was not completely ready to become heroes and set up in Colorado. Then, in Thunderbolts #20 by Busiek and Bagley, they finally got their chance to find redemption when Hawkeye showed up and offered to serve as their leader. Baron Zemo, one of the most despicable villains in history, may have created the Thunderbolts as part of his villainous plans, but the team, in its ever-evolving form, still ultimately remains a chance for villains to do some good in the Marvel Universe after 20 years.