Although the MCU has been around for well over a decade at this point, its history is dwarfed by the extended history of Marvel comics more generally. In that long history, Marvel has introduced us to many of the most legendary villains of all time. Often, those villains square off against an individual hero.
Sometimes, though, the most powerful among them also face off against the Avengers more generally. Most of them don’t manage to lodge a victory, but this list is composed of the Marvel villains who were able to really give Earth’s mightiest heroes a run for their money, and sometimes even lodge a rare win against them in one way or another.
10. Loki
The trickster god was the first villain the Avengers ever faced, and he may still be their most iconic foe. In the movies, Loki is powerful, but nowhere near the powers of the biggest baddies that the Avengers have ever faced. In the comics, though, Loki is significantly stronger, and his cunning makes him one of the most dastardly foes that the Avengers will ever come up against. It’s no wonder they started with him in the movies too.
9. Ultron
The idea of a robot or AI system running amuck feels a bit played out these days, but Ultron remains one of the more terrifying versions of this particular trope. In every version of his story, Ultron is the creation of an Avenger, and he’s also one of their most relentless opponents.
It may be precisely because he was created by them that Ultron feels like such a constant thorn in their side and not the kind of thorn that can be easily dealt with either.
8. Doctor Doom
Doctor Doom has yet to be introduced in the MCU, but he’s probably the most iconic villain that is still off the table. He’s usually paired with the Fantastic Four, but few characters in the broader Marvel canon possess the same combination of power and cunning that he does.
He’s exceptionally cruel, but it’s his skill as a schemer that makes him so difficult to beat. The Avengers like to solve problems with their fists, and Doctor Doom has made it exceptionally difficult for them to do that on more than one occasion.
7. The Kree
They may have been largely dealt with in the MCU, but the Kree remain a pretty consistent foe for the Avengers in the comics. Because of their advanced technology and their sheer numbers, the Kree have access to powers that only a select few people on Earth can equal.
Naturally, that combination makes the Kree a particularly difficult foe for the Avengers, and when they have squared off, the conflict has been much closer than you might imagine.
6. Thanos
Perhaps the Avengers villain that MCU fans are most familiar with, Thanos’s motivations in the comics are slightly different, but his power remains a constant. He’s a true force to be reckoned with, and one that inspires a legion of his own that also has to be contended with. There’s a reason he was the culmination of the entire MCU project through 2019: Thanos is that big of a threat, and that difficult to contend with.
5. Mephisto
Mephisto is both sinister and silly in a way that the MCU hasn’t really attempted yet. His main desire is to steal people’s souls, and his supernatural powers make him a difficult enemy to wrangle with.
Numerous Avengers have fallen under his spells at one point or another, and his thousands of years of experience make him hard to trick. He may not actually be the devil, but he’s the closest thing the Marvel universe has to one, and that means he should be viewed as the fearsome threat he is.
4. Kang the Conqueror
Kang is set to be the new arch-baddie of the MCU, and he’s a great pick for a number of reasons. The multi-versal baddie’s only goal is to find and conquer the world’s mightiest warriors from across the multiverse. Kang’s power is harder to reckon with than a villain like Thanos in part because it’s not just in his strength, it’s also in his enormous intelligence. This is a normal man who has found a way to conquer the universe, and that’s what makes him so terrifying.
3. The Scarlet Witch
The true power of the Scarlet Witch is so terrifying that it’s hard to write her into a story without allowing her to totally overpower everyone else. Wanda Maximoff is not always a villain in the comics, but when she is, she quickly becomes one of the Avengers’ most fearsome foes.
When Wanda is driven mad by loss and grief, she becomes responsible for the mass extinction of more Avengers than any other character in the history of the comics. She has enough power to wipe Earth’s mightiest heroes off the map without even breaking a sweat. Luckily, she usually decides not to.
2. The Celestials
We got our first look at the Celestials in The Eternals, and they seem like the kind of force that it’s difficult to even imagine reckoning with. These are the creators of the universe, and as such, they have more power than almost anyone in the MCU.
The Eternals are usually the ones made to deal with the Celestials, but the Avengers have been hard-pressed to defeat them whenever they’ve crossed paths. Given how the Celestials have been introduced into the MCU, it’s possible that they could have a role to play in upcoming stories across the larger universe.
1. Korvac
Although he started as just a regular dude, computer programmer Michael Korvac ultimately became the clear choice for the most powerful foe that the Avengers ever faced. Korvac gained that power after alien invaders transformed him into a cyborg, and he was ultimately exposed to the Power Cosmic and gained the power to reshape reality.
While his goal was to create a utopia, his conflict with the Avengers ultimately led him to murder them all. It was only Korvac’s own remorse, and his willingness to sacrifice himself, that returned the Avengers to life.
