This year's Avengers: Infinity War ended on a depressing note as the Mad Titan Thanos snapped his fingers and wiped out half of all life in the universe.
Next year's fourth Avengers movie will see the remaining heroes rallying to fight back against the prune-chinned villain — and this time they'll have backup in the form of Brie Larson's Captain Marvel, who'll make her MCU debut in her solo movie prior to Avengers 4.
She's expected to be the most powerful superhero in the MCU to date, meaning she's expected to be a key player when it comes defeating Thanos.
As a result, several fan theories have been conceived regarding how exactly she might do it — and not only are they all over the internet, we've also got a few of our own.
Here are 10 of those theories, ranging from the sublime to the almost ridiculous.
A straightforward beatdown
A lot of theories of this nature are extremely convoluted, but we think Captain Marvel could be so physically strong and durable that she simply beats the heck out of Thanos and takes the Infinity Stones from him by force.
She's set to be more powerful than Thor, Hulk, or anyone else Thanos has faced before — and she could be of a level that the Mad Titan can't handle, even when he's wielding all six Infinity Stones.
It would undoubtedly be extremely satisfying to see the villain brutally beaten down, after he so nonchalantly and mercilessly erased so many people from existence, including several beloved characters.
Another item of power
You may think that no items in the Marvel universe are as powerful as all six Infinity Stones combined, but if the comic books are anything to by, that's not actually true — and we believe there could be something out there in the MCU that can overpower Thanos while he's wielding them.
The Heart of the Universe, for example, is an energy source of infinite proportions — and possessing it makes the user the supreme being of the universe.
Thanos got his hands on it in the comics and said he'd never been more powerful — not even when he was wielding the Infinity Gauntlet — and given Captain Marvel's knowledge of the cosmos, she could both know about it and be powerful enough to wield it against the villain in the MCU.
We know the shapeshifting Skrulls will be making their MCU debuts in Captain Marvel's solo movie — the last MCU movie before Avengers 4 — and we believe that might not be a coincidence.
The Skrulls will be the movie's antagonists and Captain Marvel will be fighting against them, rather than alongside them, but the confrontation will take place in the 1990s and a truce might have been agreed between the two parties by now.
With that in mind, we believe there's an outside chance the Skrulls' shapeshifting could be utilized to defeat Thanos. Captain Marvel could potentially recruit them to pose as one of the Mad Titan's allies and trick him into removing the Infinity Gauntlet, or she might even absorb their powers in order to do it herself — it could happen, as we still don't know what this powerful new version of the character will be capable of!
It's long been known that past scenes in the MCU will be revisited in Avengers 4, so it's not really a theory to suggest time travel will be involved in the movie — but exactly what that time travel will entail is certainly still open to debate.
A Reddit user has suggested that Tony Stark might build his own Infinity Gauntlet, then recruit Scott Lang to travel through time with him via the Quantum Realm. The pair will then retrieve the six Infinity Stones from different time periods and level the playing field against Thanos.
We believe that, given how powerful she's expected to be, Captain Marvel may be the character chosen to wield it against the Mad Titan and, ultimately, defeat him in the movie's epic climactic battle.
There's a theory suggesting that Captain Marvel will become trapped in a time loop at the end of her 2019 solo movie, sacrificing herself for the greater good and condemning herself to fight against the Skrulls forever.
One Reddit user has suggested that, in one of the Captain Marvel end credits scenes, Tony Stark and Scott Lang will rescue her from the time loop and bring her to the present day — at which point some of Stark's tech will come in very handy.
The B.A.R.F. technology that was introduced in 2016's Captain America: Civil War will be used to help her better understand their predicament, by bringing her up to speed with all the MCU's major events — psionically taking her to specific moments like the Battles of New York and Sokovia. At that point, knowing what's at stake, she'll be able to use her existing knowledge and experience to take Thanos down.
Breaking the Soul Stone
There's a very prominent theory that, when Thanos snapped his fingers at the end of Avengers: Infinity War, the victims of the snap didn't actually die — they actually ended up in the Soul World (the orange-tinted world inside the Soul Stone).
We've already seen Gamora — and, indeed, Thanos himself — inside this mysterious realm, so we know it exists in the MCU, and a Reddit user has suggested Captain Marvel will be the one who rescues the victims of the Mad Titan's finger snap from there.
Whether it's because she'll be the only one powerful to wield it or the only one powerful enough to break it (if either of those things are what it takes to set the victims free), there's a good chance she’ll be the solution to releasing everyone from inside the orange stone.
While most people think the victims of Thanos' snap are either inside the Soul Stone or simply erased from existence completely, one Reddit user has suggested they might actually be in an alternate dimension.
The idea is that Thanos used the combined power of the Space, Reality, and Mind Stones to send them to a parallel universe instead — which is undeniably a very interesting idea.
The concept of multiverses has already been introduced in the MCU and Marvel Studios hired a quantum physics advisor as a consultant for the franchise. Given that there's a theory in theoretical physics regarding "daughter universes" (whereby every choice you make or don't make leads to the creation of another universe), this one seems extremely plausible.
In the comic books, courtesy of experimentation by the alien race known as the Brood, Carol Danvers has proven herself capable of transforming into a new, more powerful form known as "Binary."
As Binary, Danvers is able to tap into the power of a white hole, which exponentially increases her physical attributes and indeed her more esoteric powers.
One Reddit user has posited that Captain Marvel might utilise her Binary form in Avengers 4, as a means of defeating Thanos. The idea is that her energy manipulation powers would increase to the point that she could control the Infinity Stones without even needing to take them from the Mad Titan — and that would allow her to undo what happened when he snapped his fingers.
Recruiting an army
There's no doubt that the heroic ranks of the MCU took a massive hit in Avengers: Infinity War, so even the assistance of Captain Marvel, Ant-Man and Hawkeye might not be enough to make a notable fightback against Thanos.
With that in mind, one Reddit user has suggested that Captain Marvel might lead a plan — along with Thor — to recruit an army to go up against the Mad Titan in Avengers 4.
It would make sense to see the two most powerful heroes in the franchise gathering the best warriors they know to save the universe. Thor could recruit the likes of Valkyrie, Sif, and Korg, while Captain Marvel could recruit the best Kree warriors and whichever other formidable allies she met during her time fighting for what's right in the cosmos.
Another Infinity Stone
Classically, it's widely accepted that there are six Infinity Stones — Reality, Space, Time, Soul, Mind and Power — and that certainly seems to be the case in the MCU. However, there have been others in different media.
The most prominent of the others in the comics is the Ego Stone (or the Ego Gem as it's known in the source material) and it contains the consciousness of the powerful cosmic entity known as Nemesis. If Captain Marvel possesses it in the MCU, she could potentially use it against Thanos.
At least that's what one Reddit user has suggested, citing the fact that Captain Marvel has been known to possess a "seventh sense" in the comics, which would make her utilization of the seventh Infinity Stone very appropriate indeed.
Avengers 4 opens on May 3, 2019.