There is an old rule of writing that the hero is only as good as their villain. Sometimes, this refers to the villain’s intellect and motive -- the orderly world of Batman would never stand out so much without the chaos of the Joker, for instance. And sometimes it’s raw power, as the X-Men could overwhelm most bad guys, but against Magneto (someone who can destroy the entire planet), they are forced to get creative. When it comes to the Avengers, Thanos definitely meets both criteria. He is a smart and calculating villain who has an interesting motive in he genuinely believes he is helping the universe out, and in this way, he’s a hero in his own mind. And he has the raw power to back it up, too. As powerful as the Avengers and their allies are, they are seemingly nothing against a man who controls all of space and time with his Infinity Gauntlet.
Infinity War ended with the unthinkable -- Thanos won, and he managed to wipe out half of all life in the universe. We saw several of our characters heartbreakingly turn into dust. And fans can’t help but wonder, if the Avengers couldn’t stop him at full strength before he had all the Infinity Stones, how could they possibly stop him now when Thanos is all-powerful and they are at half-strength? We’ll find out in Avengers 4, but fans hate the wait. That’s why they’ve been speculating about all of the different ways Thanos might be defeated. We’ve collected the best theories together, and you can judge for yourself what is most likely to happen.
21 THANOS SNAPS BACK
Obviously, most fans are focusing on Thanos as the big bad guy and wondering how our heroes can defeat him. In fact, that’s why you’re reading this list. But what if something unexpected happened? According to some fans, the only person that can defeat Thanos is the Mad Titan himself.
This theory hinges on the idea that Thanos seemed much more somber after he got the Stones. And that look of “peace” on his face at the end might be thoughtful ambivalence. It’s possible becoming all-powerful will make him all-knowing. And realizing that no one should have the power of a god, he will destroy the Gauntlet after undoing his snap.
20 STONE SEEKERS UNITE
The most surprising cameo in Infinity War was Red Skull. He dropped a few different plot bombs on us, including the fact that he once sought the Infinity Stones and is now cursed to help guide those seeking the Soul Stone. Some fan theories hold that he might actually be the key to defeating Thanos.
Why? Well, no one would know more about the Infinity Stones except for other people who had tried to find all of them. In addition to Red Skull, there are potentially many more Stone seekers out there. If they all join together, they may be able to beat Thanos and nab the Stones, creating new villains for our heroes to defeat.
19 IRON MAN: SORCERER SUPREME?
When RDJ's not busy making jokes (or are they?) that turn into fan theories, he’s goofing around on set (and also creating fan theories). For instance, a leaked photo showed him on set wearing Doctor Strange’s cloak. This led to the theory that Tony Stark will become the Sorcerer Supreme and defeat Thanos.
Sound crazy? Maybe not. In Strange’s world, magic is something that can be studied, quantified, and understood. In this sense, it’s not impossible that mechanical genius Tony Stark could figure it all out. And him ascending as a magical being would explain why we no longer see Tony Stark after the next movie, all without ending him.
18 THANOS IS ALREADY GONE
We’ll go ahead and say it -- this theory is maybe the one that is least likely to be true. But it’s also one of the coolest theories out there, and one that would turn Infinity War into a twist ending. Instead of Thanos losing in the next movie, what if he is already no longer alive?
According to the theory, Thor’s blow with Stormbreaker was actually a fatal one. And while Thanos had enough strength to snap, everything else from his perspective (including seeing his deceased daughter and resting in a kind of paradise) are all things simply occurring in his head!
17 THE MULTIVERSE
Some fans have an interesting variation of the theory that Ant-Man traveling through time might hold the key to stop Thanos once and for all. They think that instead of traveling to his own past, Ant-Man might instead use the Quantum Realm to access another dimension.
In the world of Marvel Comics, there are countless different realities that all comprise the “multiverse.” In most respects, these different universes are similar to the one we know and love. If Ant-Man can make it to another universe, he may be able to gather an entirely new set of Infinity Stones and another Infinity Gauntlet to help defeat Thanos.
16 SKRULLS DEFEAT HIM
From the post-credits scene of Infinity War, we know that Captain Marvel will play a major role in Avengers 4. And we know that her own movie, a prequel, is going to feature the Skrulls. Some fans have put two and two together and think that the Skrulls will actually defeat Thanos.
The Skrulls aren’t super-powerful on their own, but they can shapeshift with the best of them. This means it would be possible for one of them to get close enough to Thanos to trick him and take the Gauntlet, effectively defeating Thanos with a simple deception and leaving the universe with a new threat.
15 IRON MAN FIGURES OUT THE STONES
This first theory doesn’t have a lot of specifics to it. However, it might be the most grounded theory on this list. Well, the theory is that Tony Stark may be the only man in the universe who can figure out how to use the Infinity Stones to reverse what has happened.
Remember, Doctor Strange was willing to give up the Stone he swore to protect in exchange for Tony Stark’s life. It seems like out of all those possible outcomes he forecasted, Tony is absolutely vital to the only one where the good guys win. And it makes a lot of sense, as this is like another mechanical problem for Stark to solve, just on a universal scale.
14 GAMORA?
There are several theories on this list that involve the idea of the Soul World, but just what is this place? Basically, it’s an entire dimension inside the Soul Stone where the victims of the Stone’s wielder end up. And it looks like we get a glimpse of this towards the end of Infinity War when we see a child-like Gamora inside an orange-hued world.
As an adult, Gamora has been prepared to kill Thanos for years. This theory hinges on the idea that she will manage to somehow escape the Soul World and enact her revenge. Does this sound crazy? Keep in mind that these movies are loosely based on a comic series where Gamora managed to escape the Soul World and help stop her father.
13 CAPTAIN MARVEL
Some of the theories on this list are quite outlandish. Others are what the gambling world might call “even money.” This next theory is one of those even money bets. What is it, exactly? It involves Captain Marvel arriving and helping to defeat Thanos once and for all.
As you’ll recall, Nick Fury summoned Captain Marvel right before he disappeared. We’re going to get her '90s-set solo movie pretty soon, but the implication is that Fury is confident enough in her abilities that she is his “dial in case of apocalypse” person. If she’s good enough for Fury, she’s good enough for us.
12 NEBULA IS THE WINNER
As we said, some of the items on this list hew pretty closely to what happened in the original comics. That’s true of this theory, which holds that Nebula will manage to defeat her father, most likely by wresting control of the Gauntlet away from him and possibly becoming our true villain.
That’s what happened in the comics arc, of course -- a tortured Nebula got the Gauntlet and forced Thanos to help the heroes beat her. This is because she is unhinged enough to possibly wipe out all remaining life in the universe. We don’t know how likely this is, but Nebula definitely deserves her vengeance on Thanos.
11 ANT-MAN TRAVELS IN TIME
Compared to things like Infinity War, the Ant-Man movies are much quieter hits. However, a post-credits sequence for Ant-Man and the Wasp seems to hint that Ant-Man will be instrumental in defeating Thanos. This is all due of the Quantum Realm.
The sequel strongly hints that the Quantum Realm could help someone hop back and forth in time. If this is the case, Ant-Man could go back (say, to the battle of New York) and start getting everyone ready to fight Thanos. This theory is fueled by some leaked photos that show Ant-Man alongside Cap in his old-school outfit, making fans thing time-traveling will be afoot. In addition to beating Thanos, this may help reset this universe for future movies.
10 THANOS TRAVELS IN TIME
As we mentioned, many fans are focusing on the idea of time travel as the key to defeating Thanos. For such believers, the smart money is on Ant-Man using the Quantum Realm to travel to the past. However, one theory holds that this is all wrong… and it’s actually Thanos that has traveled to the past.
This theory hinges on that final shot, with Thanos resting on a peaceful farm on a distant planet. It’s not immediately clear what planet this is, but it seems likely it’s Titan, his home planet, looking green and lush instead of a blasted hellscape. If Thanos is in the past, and if the Gauntlet isn’t fully working (remember how it smoked), our heroes can take him out.
9 SOUL STONE TAKES HIM OUT
You’ve probably noticed by now, but many of these theories share a common DNA. Earlier, we had the theory where Gamora manages to escape the Soul Stone and defeat Thanos. This next theory riffs off of that and says that it won’t just be Gamora, but everyone else.
Remember, Soul World houses all the victims of the Soul Stone wielder. By the end of Infinity War, it would theoretically be filled with half the universe. If they can somehow organize and escape, they might just have enough power to take Thanos out once and for all, saving the universe.
8 HAWKEYE IS THE SECRET WEAPON
Obviously, most of these theories come from MCU fans. Every now and then, though, one comes from within the MCU itself. For instance, at an event in Singapore, Robert Downey, Jr., claimed he thought that only Hawkeye could defeat Thanos. Knowing the actor’s sense of humor, this was probably a joke… but what if it’s not?
In the comics, Hawkeye has had some moments where he’s a lot like Batman. If he has the time and resources to set something up, he can take out anyone and, in fact, not that long ago, he took out The Incredible Hulk with a single arrow. If he has enough support, it may very we be Hawkeye who takes out the big guy.
7 THANE STOPS HIM
Considering that the MCU is based on Marvel Comics, it’s not uncommon for fans to look at the comics to figure out what comes next. That’s why a few fans think we have a dark horse contender for who will defeat Thanos in his very own son, Thane.
In the MCU, “the Children of Thanos” alternatively refers to his lieutenants, his victims, and to people he has adopted. In the comics, though, Thane is a biological son, and he’s also an Inhuman. This combination of genetics means that he is powerful enough to beat his dad up… and maybe we’ll meet him on-screen before you know it.
6 DRAX GETS HIS VENGEANCE
Many of these theories are really complex and require a lot of creative thinking. However, some theories are out in the open, staring us in the face for years. For instance, one fan theory holds that Drax will manage to escape the Soul World and get his final vengeance on Thanos.
As you know, Drax still mourns his family that Thanos took away from him. And as recently as Infinity War, we saw how Drax still gets insanely (and rightfully) blood-red mad at the sight of Thanos. It would be a good completion to his arc (and a fan-pleasing moment in general) to let Drax complete his quest and rid the universe of Thanos, once and for all.
5 THERE IS ANOTHER STONE
This is another theory that is more of a longshot than others. However, it’s not impossible, and there is some sketchy precedent for this in some weird sources like Marvel video games. So, what’s the theory? It involves the Avengers finding a seventh Infinity Stone.
Obviously, the plan Thanos hatched hinged on him getting all of the Infinity Stones and gaining a kind of god-like power. This theory holds that there is another Stone out there he doesn’t know about, and gaining this Stone might give an Avenger (like Tony) enough power to wrest control of the Gauntlet from Thanos.
4 WE DO TRADE LIVES
While we call it “Avengers 4” for the moment, the next big movie is basically going to be “Infinity War, part 2.” That means things from the first movie are clearly laying the groundwork for the next. And according to some fans, Captain America has already told us what this “endgame” is going to be about.
Cap was adamant about the idea that “we don’t trade lives.” However, Vision reminds him that this is exactly what he was willing to do back in the second World War. Some fans think Cap and others will manage to trade places with people in Soul World, effectively ending their own lives to rescue the heroes who will ultimately defeat Thanos.
3 LOKI VICTORIOUS
Thanos is obviously a very big threat, even before he has all the Stones in his possession and Infinity War establishes this early on by having Thanos crush the life out of Loki. Adding insult to injury, Thanos even mocks the fallen trickster, saying “no more resurrections.” However, what if he was wrong?
Few people understand Thanos as well as his one-time employee Loki. And perhaps no one understands cheating the end like Loki. Some fans are hoping that not only did Loki find a way to survive Thanos, but that he will be instrumental in finally landing his blade inside Thanos, ending the threat once and for all.
2 X-MEN ARRIVE
This next theory is not very likely due to the realities of Disney/Fox merger details and the timing of filming. Nonetheless, fans can dream, can’t they? And in this case, some fans are dreaming about something very particular in the X-Men. Perhaps these mutants will be the force that undoes Thanos?
With things like the Reality Stone in play, it’s possible to make universal changes, either by intent or accident. Now that Disney has the rights to the X-Men, some fans are hoping that they arrive (either via another dimension or an alteration to “our” MCU reality) and lay a whopping on Thanos. We’d pay double to see Wolverine fighting Thanos on the big screen.