One of the things Marvel Studios has long been known for is its long-term planning. Back when the studio was still in its infancy, it was still slowly working towards creating a cohesive universe where characters could pop from one film to the next, culminating in the formation of the Avengers. It's a model that was a complete risk, but it's one that paid off in spades. Now, Avengers: Infinity War, a film that is essentially the first part of a conclusion to a story that has been unfolding over 10 years, is the biggest movie in the world, and it has just set the stage for the final chapter of this sprawling saga.

Throughout this decade, Marvel slowly introduced the Infinity Stones, powerful cosmic relics that would come into play in a very big way in Infinity War. But these Stones aren't the only cosmic thread that has been running throughout the Marvel Cinematic Universe. For a good while now, the MCU has also been teasing the Marvel Multiverse, an endless number of parallel realities. Infinity War gave us our biggest tease to the Multiverse yet, but it was only the latest. Here, CBR lists 15 hints of the Multiverse we have already seen on-screen.

* Black Panther art in Feature Image Brice Cdn.

15  AN OFFICIAL NAMEDROP IN DOCTOR STRANGE

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Before 2016's Doctor Strange film, we had no idea if Marvel Studios would ever go as far into its sci-fi and comic book concepts as by introducing the theory of the multiverse, of alternate realities and dimensions and parallel universes that are living side-by-side with one another. However, with the arrival of a movie starring everyone's favorite Master of the Mystic Arts, it seemed more likely than ever. Then, the film not only brushed on the concept, it gave us an entire crash course meant to introduce an unfamiliar audience to the Marvel Multiverse.

Thanks to her, we learn that these wizards harness the energies from the Multiverse to create magic.

When Stephen Strange first meets with the Ancient Once, he is thrown across dimensions, as we are taken on a trippy trip through other realities. Whether they are infinitely small or cosmic in width, these realities take us for a spin as Strange flies through each and every one of them, each more strange and terrifying than the last. What's more, while the Ancient One starts teaching Strange on the mechanics of magic, she even goes so far as namedropping the Multiverse, using the word to describe to her pupil where the magic they wield comes from.

14 THE QUANTUM REALM

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In the latest trailer of Ant-Man and the Wasp, we saw that the Quantum Realm would factor into the story in a very big way. The microscopic world was one that was mentioned in the first Ant-Man film, before Scott Lang made the ultimate sacrifice to defeat his enemy. By going subatomic, Scott found himself in another Realm -- another reality entirely. Although he managed to make it out of this other dimension, it appears as if the Ant-Man and his new partner the Wasp will once again venture into this other realm. But they won't be the only ones affected by it.

In fact, in the sequel's trailer, we saw that a villainous woman will steal some of Hank Pym's technology and somehow harness the power of the Quantum Realm. Whether this occurs by accident or on purpose, we have seen that this villain will be surrounded by the energy found in the Quantum Realm, an unstable force that will allow this woman to phase through solid objects – something that will earn her the codename of Ghost. The trailer also showed us that this energy can be quite dangerous, and that it could lead to catastrophic explosions. Therefore, it appears as if Ant-Man and the Wasp will give us even more information on the Marvel Multiverse.

13 THE POWER OF THE INFINITY STONES

In 2014's Guardians of the Galaxy and the just-released Avengers: Infinity War, we are informed that the Infinity Stones were created at the dawn of time, that they were six singularities that were created when the universe was born. This could mean that before the Stones were concentrated, the powerful energy that they housed existed outside of time, and outside of the known universe.

Whatever there was before the Big Bang, the Infinity Stones were a part of it.

After all, no one knows what there was before the Big Bang. Not the powerful Eye of Agamotto, and not even the Celestials. The Infinity Stones are perhaps remnants of the pure power of the Multiverse. Their power has no equal in the Marvel Cinematic Universe, and it can affect everything at once. Perhaps even more than one universe. If Doctor Strange and the Ancient One harness their power from the Multiverse, then perhaps it's only a fraction of what the Infinity Stones are able to harness. Perhaps these Stones harness the power of all the combined universes. That is, unless there is a version of them in each parallel universe, though in the comics gauntlets can only work in their own universe.

12 DOCTOR STRANGE'S LOOK INTO THE FUTURE

In Avengers: Infinity War, which you can now see in theaters (if you haven't already), the Mad Titan Thanos proceeds to collect all the Infinity Stones in hopes of wiping out half of all life in the universe. While most of the Avengers fight to protect the remaining Stones from falling into the supervillain's grasp, Doctor Strange floats above the ground of Titan and uses the Eye of Agamotto to peek into all the possible outcomes of their confrontation with Thanos. Peering into the future, Strange goes through millions of scenarios where the Avengers lose against Thanos. The thing is, Strange lives through these possible futures; he sees them and experiences them.

This means that these millions of possible scenarios actually happened... somewhere. These are effectively alternate realities, or other universes where Thanos won against the Avengers. With each new outcome that Strange tried, a new parallel reality was created. We didn't get to see them, but he sure did -- millions of them, in fact. Who knows what each outcome led to, which characters died and what their respective futures would be. As far as the audience was concerned, Doctor Strange may have been hovering above the ground, but he actually visited the Multiverse. In fact, he might have helped create some alternate realities.

11 CAPTAIN MARVEL'S WHEREABOUTS

If you stuck around until after the credits of Avengers: Infinity War, then you got to see the after-credits scene of the film – and what a scene it was. As if the ending of the film itself didn't pack enough of an emotional punch, you had to watch as Thanos' finger snap took away more of your favorite characters. It started with Maria Hill, then continued with Nick Fury. But before Nick disappeared into ash, he had the time to send out a distress signal. It took a little while for the signal to get through, but when it finally established a connection, we saw that he was calling the one and only Captain Marvel.

If she resurfaces without having aged a day, than it's quite possible that she was lost in another dimension.

But where is Captain Marvel? No one knows. What we do know is that her origin movie will come in March 2019, and that it's set in the 1990s. This means that she was around before the Avengers were ever assembled. So where has she been hiding all this time? If she resurfaces without having aged a day, than it's quite possible that she was lost in another dimension -- or another universe entirely. What else could explain the simple fact that the most powerful superhero in the Marvel Cinematic Universe hasn't made her presence known before then? If you ask us, the signal took this long to reach Captain Marvel because it had to go through a few universes before it reached her.

10 SOUL WORLD

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In Avengers: Infinity War, Thanos learns that the mythical Soul Stone is on a barren planet called Vormir. Once he finds his way there, he finds the Stone's keeper, the Red Skull, who informs him that the Soul Stone is almost sentient, and that it requires a sacrifice to be wielded: a soul for a soul. Although it breaks his heart, Thanos has no choice but to sacrifice his favorite daughter Gamora by throwing her down a cliff to her death. When Thanos regains consciousness, he now has the Soul Stone in his grasp, and Gamora is gone.

But it just so happens that Gamora might not be as dead as everyone believes. When Thanos snaps his fingers to annihilate half of all life in the universe, he briefly visits another plane of existence where he meets with a young version of Gamora. This ethereal location appears to be Soul World, a pocket dimension housed inside the Soul Stone. This Soul World is able to hold the souls of the dead, and it can even be visited by those who would wield the Stone. Since it effectively is another reality, this could very well be seen as another hint at the Marvel Multiverse. After all, if anyone besides Thanos can visit this world, it would be Doctor Strange. Or maybe it's even Adam Warlock, who is set to be introduced in Guardians of the Galaxy Vol. 3.

9 THE FINGER SNAP

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Once the Mad Titan collected all six Infinity Stones, we were warned that he would be able to accomplish his nefarious goals with nothing but a snap of his fingers. Gamora warned us, and Thanos himself threatened the Avengers with it. But nothing could prepare us for the moment when the Mad Titan actually went through with it. With a snap of his fingers, the supervillain wiped out half of all life in the universe. While others watched on, helpless, we witnessed the departure of characters like Bucky, the Black Panther, Spider-Man, Mantis, Groot, Drax, Star-Lord and the Scarlet Witch, who all disappeared.

When Thanos snapped his fingers, did he actually create a parallel universe?

The original six Avengers remained, along with War Machine, Rocket and Nebula. Faced with defeat, they now stand hopeless. Some fans have now begun to theorize that when Thanos snapped his fingers, he actually created a parallel universe that splintered away from the main MCU. That, or perhaps the ones who disappeared were perhaps sent off to another reality. It's therefore possible that this snap is another hint at the Marvel Multiverse. Whatever the case may be, in order to save everyone, perhaps the Avengers will have to set things right, and return things to the way they were before the fateful finger snap.

8 DORMAMMU AND THE DARK DIMENSION

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Early on in 2016's Doctor Strange film, Stephen Strange was taken on a tour of the Multiverse, where he saw everything from the far reaches of space, to the Quantum Realm and the Dark Dimension. There, he caught a glimpse of its evil ruler, Dormammu, an ancient force of destruction. But as far as we were concerned, Dormammu was still confined to his own dimension. However, with the help of his devout follower Kaecilius, the Dark Dimension was allowed to bleed into Earth itself. In Hong Kong, Strange, Wong and Mordo fought to keep Dormammu and his dimension at bay, and the Sorcerer Supreme eventually succeeded with the help of the Time Stone.

But we still saw the potential danger that another reality bleeding into the real world represented. Were it not for the world's sorcerers, Dormammu would have been successful in invading a dimension other than his own. This was perhaps one of the biggest hints we had at the Marvel Multiverse, where we saw an event that seemed to borrow a bit of inspiration from the “Incursions” that played such a big role in writer Jonathan Hickman's New Avengers run. The comic books showed what would happen if two realities collided, and that is what almost happened in Doctor Strange.

7 BLACK PANTHER'S ANCESTRAL PLANE

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In the Black Panther film, viewers learned all about the culture of the African nation of Wakanda, of their many practices -- one that involved allowing the newly-christened King to visit the Ancestral Plane of Wakanda, a plane known as the Djalia in the comic books. While such a name is not given in the film, we do visit it twice, after both T'Challa and Killmonger ingest the mystical heart-shaped herb that gives the Black Panther his power. There, the men visit this ancestral plane, where they are allowed to commune with their deceased fathers.

It is a very spiritual place, but also one seeped in mystery.

The ancestral plane has proven to be a place where the dead can interact with the living. There is no telling how many souls inhabit it. Does it contain only the souls of deceased Wakandans? We may never find out, but we know enough about this plane that it could be a pocket reality within our own. If Doctor Strange were able to access this mystical plane, then it could be surmised that the Wakandan Ancestral Plane qualifies as another reality. It might be another plane of existence, but it can still theoretically be counted as part of the Marvel Multiverse.

6 THE FEAR DIMENSION

While the movie side of the Marvel Cinematic Universe has taken its time in introducing the Marvel Multiverse, the television side has given us some very direct ties. In fact, recently on Marvel's Agents of S.H.I.E.L.D., Phil Coulson and the rest of his band of merry agents went up against the forces of another reality. During the currently-running fifth season of the series, an explosion led to the destruction of several monoliths that allowed for inter-planetary teleportation. The destruction of these powerful relics had an unforeseen consequence, however, in that it created a rift in space and time, and reality itself.

This rift was actually a small tear. It was essentially a door that led to another dimension, something that the series dubbed the Fear Dimension. Pure fear bled out from this reality and into the world of the Agents of S.H.I.E.L.D., taking the form of whatever they feared most. It would take the use of the powerful element known as Gravitonium to close the rift, a mission that proved extremely dangerous. While the door to the Fear Dimension was effectively closed, the series did manage to introduce another alternate dimension, one that can now be added to the Marvel Multiversal catalog.

5 K'UN-LUN, MYSTICAL HOME OF THE IRON FIST

Surprisingly, the more grounded world of Netflix's various Marvel superhero series actually managed to give us a hint at the Marvel Multiverse. Of course, the gritty streets of New York, where Daredevil, Jessica Jones, Luke Cage and the Iron Fist fight to protect the citizens from criminals, gangsters and super-powered threats isn't the most obvious place to look for alternate dimensions and realities – but one of the six various Netflix series did manage to offer a tease. And it's one that finds itself much further East than New York.

In fact, in Danny Rand's solo series Iron Fist, we actually glimpsed part of the Multiverse.

The answer actually lies in K'un-Lun, the mystical city where Danny Rand trained to become the Iron Fist. As we know, the city only appears on Earth for a brief period of time, before disappearing from this very plane for 15 years. Where does it disappear off to? In the comics, the city leaves for a different plane of existence, and it appears to be the case on the television series. This means that K'un-Lun can also find itself in another dimension – another reality that may constitute another part of the infinite vastness that is the Marvel Multiverse.

4 WHERE IS JANET VAN DYNE?

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One of the bigger mysteries of the Marvel Cinematic Universe lies in the whereabouts of Janet Van Dyne, the original Wasp. In the Ant-Man film, it was revealed that Hope's mother had once fought alongside Hank Pym's Ant-Man, and that she had gone subatomic in order to stop a nuclear missile. We were informed that Janet was lost inside the Quantum Realm, and a possible Easter egg showed us that she was possibly still lost in there when Scott Lang briefly visited the realm. But is this really where Janet is? Has she really been lost in this subatomic universe all this time?

Perhaps not. In fact, it's entirely possible that Janet did vanish inside the Quantum Realm, before being shuffled off somewhere else entirely. There is little we know about this microverse – for all we know, it might lead to other realities. We only saw a brief section of this realm so far, and it may hold many more secrets. It's already been confirmed that Janet will have a role to play in Ant-Man and the Wasp, meaning that we might head back into the Quantum Realm in the sequel – and perhaps even further than ever before.

3 THE DARKFORCE

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There isn't much we know about the Darkforce, other than that it is incredibly dangerous. It's a dark energy that stems from another world, another reality. We have seen it both in ABC's Agent Carter series, as well as Marvel's Agent of S.H.I.E.L.D. We know that it's a power that can be harnessed, considering that we have seen both Whitney Frost and the villain known as Blackout wield its great power. Furthermore, it could even be weaponized, used to transform others into pure energy to be absorbed. It first appeared on Earth during the days of World War II during a time when it was given the name Zero Matter.

It's still uncertain where this dark energy comes from, but we do know that it arrived thanks to a rift in reality.

After the explosion of an atomic bomb, a portal to another dimension was opened, one that was akin to a black hole in the dead of space. In both of ABC's series, the Darkforce has been the subject of study, and while its secrets were never truly unlocked, it still proved to be a dangerous weapon unlike any seen on Earth. Although we don't know much about its origins, we know enough to label it a product of another reality, and a further hint at Marvel's Multiverse.

2 HELL

On Marvel's Agents of S.H.I.E.L.D., the existence of Hell was confirmed thanks to the arrival of the Spirit of Vengeance, the Ghost Rider. Although we never actually went to Hell, a few opened portals did give us a glimpse of the mystical plane, showing us a world barren of life, light and hope. This is the place where the Rider comes from, and we assume it's a place where many more nefarious creatures lie. This plane of existence lies beyond the Earth, and the Rider can access it by creating a portal with his hellfire chain, much in the same way Doctor Strange creates portals with his Sling Ring.

Hell is the place that Ghost Rider disappeared into for quite a long while. We don't know the mechanics of Hell, or if Mephisto rules there, like in the comics. But we do know that it exists on a different plane, and that it truly functions as an alternate reality, another dimension that can be accessed by a select few. We don't yet know if the Rider will return from it, but we do know that he appears to be one of the only ones who can move to and from this place. For that reason, it would appear that Hell constitutes another part of Marvel's Multiverse. It may not be a parallel Earth, but it still exists outside of the Earth's dimension.

1 AN ALTERNATE FUTURE

Most of the first half of Season 5 of Marvel's Agents of S.H.I.E.L.D. took place in a dark future where the Earth had been cracked apart. What few human survivors remained lived under the rule of a ruthless Kree lord, a villain who sold off Inhumans to the highest bidder. Phil Coulson and the rest of his team were taken to this alternate future thanks to an alien monolith that transported them in time. There, the agents learned all about the circumstances that led to this bleak future.

This alternate future is essentially a parallel universe, one that differs from the main timeline of the Marvel Cinematic Universe.

Since Coulson, Daisy and the rest of the S.H.I.E.L.D. agents returned to the present, they have been fighting to prevent this cataclysmic event from happening. This means that their actions are affecting the timeline itself, and that they are therefore creating another future for themselves. Whether they change things for the better or not really doesn't matter, because this still proves that the series is giving us more hints at the Marvel Multiverse. This dark future is perhaps one that Doctor Strange saw coming in Avengers: Infinity War, and it ranks as one possible outcome in a sea of infinite possibilities. It's an alternate universe, and therefore part of the Multiverse.