Doctor Doom has been one of the evilest villains in Marvel Comics history. He has done things that should be irredeemable yet somehow mostly stays free thanks to the fact that he is the ruler of his own country. He has killed, sabotaged other countries, and almost started world wars, yet somehow he manages to live to fight another day, rarely facing repercussions for his actions.
Victor Von Doom made his first appearance in Fantastic Four#5 by Stan Lee and Jack Kirby in 1962. Since then, he went from being a regular supervillain to the ruler of a country and a force that the world fears but can't combat. His main enemies have been the Avengers, but he has also battled Iron Man, Hulk, Spider-Man, and everyone in between, a thorn in the side of the entire Marvel Universe.
Made Latveria Subservient To Him
Doctor Doom is the ruler of Latveria, and, for the most part, his people love him. There have been moments where they rose against him, but those were often squashed in quick order, and Doom always returns to power in the end. No one in Latveria starves, and everyone has a home, but the country remains poor while Doom remains all-powerful. These people are subservient to Doom, who offers them protection but will stamp them out if anyone crosses his path.
Took Over Counter-Earth
In the mid-90s, Marvel decided to make a big change and started a period known as "Heroes Reborn." In this, Earth's heroes fought Onslaught, and the Fantastic Four and the Avengers died to beat him. However, they didn't die and woke up on a new Earth, all with new origins and new stories.
Doctor Doom was here as well. This was Counter-Earth, created by Franklin Richards. Eventually, the heroes left to go back to the real Earth, but Doom tried to sabotage them. He failed and ended up back on Counter-Earth, where he conquered it and took over as the ruler.
Invaded Wakanda
Doctor Doom wants more power and is willing to throw his weight behind any scheme to get it. He has his own country in Latveria, but he also has his eyes on other conquests. Wakanda is one of Earth's most technologically advanced countries thanks to its supply of vibranium.
Doom wanted it and started the Doomwar, where he created nanites to spy on Wakanda. He finally stormed in to take the vibranium, forcing Black Panther to do the unthinkable and render all Wakanda vibranium inert and worthless.
Used Scarlet Witch To Gain Her Powers
In Young Avengers: The Children's Crusade, Tommy (Speed) and Billy (Wiccan) set out to find their mother, the Scarlet Witch. They believed she was alive but was hiding for her own safety since the X-Men wanted her to face punishment for M-Day. They found her with Doctor Doom.
Wanda had amnesia, and soon it appeared that Doom was helping keep her safe, and the two were to be married. It was all a trick, as Doom just wanted to gain her powers. By the time it was all ended, Doom had killed Scott Lang's daughter, Cassie.
Experimented On The Asgardians
Victor Von Doom tricked Asgard. The nation floated above Oklahoma until the events of Siege when Norman Osborn set up a plan that allowed the U.S. to attack Asgard. After this, Loki convinced Asgard to move to Latveria to be under Doctor Doom's protection. This was a big mistake. Doom began to capture different Asgardians and experiment on them to discover the source of their immortality, mutilating many of them. Thor finally returned to save his people.
Used Purple Man To Conquer The World
In the Marvel graphic novel Emperor Doom, Victor Von Doom finally achieved his life-long goal: he took over the entire world. To do this, he captured a villain that he knew could help him in the Purple Man. When Kilgrave realized he couldn't control Doom, he had no choice but to allow Doom to use him to mentally force every country on Earth to name him the Emperor.
Wonder Man was the only person left standing and began to free his teammates one by one, and then Doom finally gave up, bored with what he had achieved in victory.
Made Reed Richards Kill The Thing
Doctor Doom haunts Richard Reed. It got so bad that Reed decided he was going to do the impossible; he set out for Latveria to finally take out Doctor Doom once and for all. Reed then kills Victor Von Doom and sends him to Hell.
After this terrible decision by Reed Richards, he begins to lose his mind and accidentally frees Doom's spirit from Hell, so he possesses The Thing. This led to Reed doing the unthinkable. He killed The Thing to kill Doom. The good news is that the Fantastic Four went to Heaven to bring Ben back to life.
Murdered The Woman He Loved
Doctor Doom has no problems killing people. However, he is very protective of those he loves. He even went so far as to risk his soul itself to save his mother. It seemed that Victor was turning the corner after he helped save Susan Richards' life and the life of her daughter, Valeria. However, Doom went back to normal when he decided to seek out Valeria's namesake, the only woman he ever loved. Then he sacrificed the woman to the Hazareth Three to gain magical powers so he could combine magic and science to become more powerful.
Sent Franklin Richards To Hell
While Reed Richards sent Doctor Doom to Hell when he killed him once, Doom did something even worse. Instead of just getting revenge by doing something to Reed personally, he went after Reed's son Franklin. Using the magical powers he had gained, Doctor Doom trapped Franklin Richards, a young child, in Hell. While the Fantastic Four was able to save the child, he suffered from this traumatic experience for a long time.
Secret Wars
An Incursion took place in 2015 that caused the multiverse to die. The last two Earths standing (Earth-616 and the Ultimate Earth-1610) finally collided and seemingly wiped out all life outside of a Triskelion carrying a select few surviving heroes. The Triskelion landed on what resulted from the Incursion, a new world where Doctor Doom was God, and all worshiped and followed his lead or faced a worse punishment than death.