When Thor: Ragnarok hits theaters later this year, Marvel Studios will officially be halfway through Phase 3 and one step closer to the landscape-changing event that will be Avengers 4.

There is no telling where the Marvel Cinematic Universe will go from there. Existing contracts will expire, some characters will be killed off, and some will fade into the background allowing others to have their chance in the spotlight.

Heck, Marvel may even ditch the phase format altogether and give audiences something new and fresh. All that's known for certain is that Guardians of the Galaxy Vol. 3 and the tentatively titled Spider-Man: Homecoming 2 will happen. Nothing else is guaranteed.

The reason why so little is known about Phase 4 is because all of Marvel Studios' collective energy is currently focused on the rest of Phase 3, and what a Phase it is shaping up to be.

There's the Thor-Hulk team-up due out later this year, Black Panther's solo film, the introduction of Captain Marvel, and, of course, Avengers 3 and 4. More and more information is coming out every day on what is sure to be an epic conclusion to the eleven-year story arc Marvel Studios has created.

Here are the 15 Things You Need to Know About the MCU's Phase 3.

Warning: mild spoilers ahead.

It will be twice as long as Phases 1 and 2

Fans of the MCU have probably noticed that the layouts of the first two phases have been a bit formulaic. Phase 1 consisted of Iron Man, Hulk, Thor, and Captain America solo films before Earth's Mightiest Heroes came together in the crossover event that was 2012's The Avengers

Then Phase 2 brought us Iron Man, Thor, and Captain America solo films, and Guardians of the Galaxy before Earth's Mightiest Heroes came together (again) in Avengers: Age of Ultron. Age of Ultron was originally scheduled to be the end of the Phase 1 until Kevin Feige changed his mind and tacked Ant-Man to the end of it.

That brings our totals to six films for Phase 1 and six for Phase 2. Phase 3, meanwhile is slated for a whopping ten. Thor Ragnarok will be the fifth Phase 3 film released in theaters so far and it will be followed by Black PantherAvengers: Infinity WarAnt-Man and the Wasp, Captain Marveland Avengers 4.

 The phase has already featured the introductions of Black Panther, Spider-Man, and Doctor Strange, and yet there is plenty more excitement to be had.

It will be the start of three films per year

There are those who say the only guarantees in life are death and taxes. Marvel fans know the only other guarantee is two MCU films released in theaters every year. That has been the status quo for the better part of the last decade.

With the exceptions of 2009, 2010, and 2012 (which saw the releases of no MCU films, Thor, and The Avengers, respectively), Marvel has released two MCU films every year since 2008. The studio has become a model of consistency, and its yearly output is about to increase.

Beginning this year, the number of MCU films to be released in theaters annually will jump to three, following Guardians of the Galaxy Vol. 2 and Spider-Man: Homecoming will be Thor: Ragnarok, which is set for release in November.

Next year will see the releases of Black Panther, Avengers: Infinity War, and Ant-Man and the Wasp; and 2019 is currently scheduled to feature Captain MarvelAvengers 4, and Spider-Man: Homecoming 2.

There is no telling what Marvel Studios has planned after that (since Guardians of the Galaxy Vol. 3 is the only other film announced), but considering the schedule over the next two years it's no stretch to assume three films per year will be the new status quo.

No more Jane Foster

Jane Foster and Thor in The Dark World

One criticism often leveled at the MCU overall (and rightfully so) is the lack of romance. Sure, comedy and action are the franchise's bread and butter, but would it be so hard for the universe's couples to stay together for a few films.

Pepper and Tony managed to make it work thus far, but they are the exception that proves the rule because every other on-screen couple has been practically doomed from the start.

Betty Ross and Peggy Carter only made it through one film, respectively (yes, the latter appeared in Captain America: The Winter Soldier, but that doesn't count), Black Widow and Bruce Banner's romance was hastily thrown together, and even Star-Lord and Gamora seem to be in a bit of a holding pattern.

The only other romance with any steam was the one between Thor and Jane Foster, but that too has fallen by the wayside.

According to Kevin Feige, Thor and Jane's relationship "evolved in unexpected ways" between Thor: The Dark World and Thor: Ragnarok. In other words, they broke up and she isn't likely to return any time soon.

The Winter Soldier will not appear in Black Panther

Black Panther Bucky Civil War

It's never really clear when MCU characters will show up in future films. After appearing in Iron Man 2 and The Avengers, Black Widow wouldn't show up again until three films later in Captain America: The Winter Soldier.

Tony Stark appeared solely in Iron Man and Avengers films (excluding his cameo in The Incredible Hulk) before popping up in both Captain America: Civil War and Spider-Man: Homecoming. Meanwhile Hulk, a no-show for Phase 3 thus far, is scheduled to appear in Thor: Ragnarok later this year.

Considering the end-credits scene in Civil War, which saw the Winter Soldier put into cryogenic sleep in Wakanda, many fans have wondered if Bucky Barnes will make an appearance and fight alongside T'Challa in Black Panther.

From everything we know about the upcoming film, that is not the case. When asked about it, Sebastian Stan bluntly replied, "I am not in Black Panther." Despite Marvel Studios going above and beyond to avoid leaks, it's probably best to take the actor at his word.

Infinity War will be the longest MCU film to date

Speaking of Avengers: Infinity War, Marvel Studios' nineteenth (yes, nineteenth) film slated for release in May of next year is on pace to be the MCU's longest yet.

Currently, the longest MCU films to date are Avengers: Age of Ultron (142 minutes), The Avengers (143 minutes), and Captain America: Civil War (148 minutes).

Civil War, however, didn't have Thor, Hulk, Doctor Strange, or the Guardians of the Galaxy, all of whom will appear in Infinity War. The film also has the tall task of providing Thanos' backstory, which is thus far unknown.

According to the film's co-director Joe Russo, Infinity War will be longer than Civil War by quite a large margin. Speaking with Collider Russo said, "I still have a couple of scenes that we haven’t finished from Avengers 3 that I’m shooting in the next few months with my brother, and it’s certainly gonna be a film that lives in the two and a half hour, two and a half hour-plus range."

With all those characters, two and a half hours seems about right.

Nebula's past is worse than we know

When it comes to underrated MCU characters, Nebula is one of the best. A bald extraterrestrial with blue skin and cybernetic enhancements, Nebula is without a doubt one of the more uniquely-designed characters to come out of the MCU thus far. The fact that she is the adopted daughter of Thanos and sister of Gamora only adds to the intrigue.

In Guardians of the Galaxy Vol. 2, audiences learned that Nebula received her cybernetic parts from Thanos, who replaced pieces of her with machinery every time she was bested by Gamora, and according to the actress under the makeup, that's just the tip of the iceberg.

While speaking at Florida Supercon (via Comicbook), Karen Gillan said, "We’re definitely going to continue the arc for Nebula and find out more about her past. And actually, we’re going to find out that it’s even worse than we know.” What can be worse than the forced removal of body parts and their subsequent replacement with machinery? Audiences are about to find out.

Thanos will be joined by the Black Order

Avengers: Infinity War will center around Thanos' quest to capture all six Infinity Stones. Once the Mad Titan has all six Stones and the Infinity Gauntlet, then he alone could potentially be too much for the Avengers to handle.

Until then, however, he will likely need some help taking on Earth's Mightiest Heroes and the Guardians of the Galaxy. From what we know about the movie so far, that help will come in the form of the Black Order.

The Black Order is comprised of Thanos' adoptive children, namely Corvus Glaive, Proxima Midnight, Ebony Maw, and Cull Obsidian (known in the comics as Black Dwarf).

The Black Order's abilities range from super-intellect to super-strength, and the four of them, in addition to Thanos and the power of the Infinity Gauntlet, will undoubtedly make formidable opponents unlike any the Avengers have seen before.

Multiple Stan Lee cameos have already been shot

Stan Lee MCU Cameos

Over the course of sixteen films, Stan Lee's MCU cameos have become the stuff of legend. In fact, the creator of many of Marvel's most iconic characters has had so many different appearances in MCU movies that fans theorized he may be playing the role of Uatu the Watcher, one of the oldest beings in the cosmos.

This theory was nearly confirmed in Guardians of the Galaxy Vol. 2 when it was revealed that Lee was actually an informant for the Watchers and had been reporting on the Avengers for quite some time.

Lee is now 94-years-old and will be 95 this December; thus, having him fly to a new set every time another film is in production is a lot to ask. To ease the burden on Lee, Marvel films multiple cameos at once.

In fact, Guardians of the Galaxy director James Gunn revealed that he shot four Lee cameos in one session. It's entirely possible that Lee's future cameos will be shot sooner rather than later to ensure the legend appears in each Phase 3 film.

Marvel is taking every precaution to avoid leaks

Tom Holland Spider-Man

Keeping a movie's secrets in-house can be difficult considering all of the people involved in the film-making process. Avoiding spoilers in a franchise that consists of multiple films is damn-near impossible. Yet Marvel Studios has managed to do just that without any major leaks (despite Tom Holland's best efforts).

Sterling K. Brown (who will play N'Jobu in Black Panther) revealed some of Marvel Studios' tactics for avoiding spoilers. These include avoiding all hard copies of scripts and instead using online links with a time limit for viewing. Actors also sign out their scenes for the day and are forced to return them after shooting is complete.

Marvel is also apparently limiting the amount of information it divulges to Tom Holland for fear that he will accidentally reveal some significant details about the films to come. The actor even went so far as to burn a copy of his script after he forgot to return it to producers. Now that's dedication.

Michelle Pfeiffer is playing Janet van Dyne

One of the larger plot points at play in 2015's Ant-Man centered around Janet van Dyne, mother of Hope and wife of Hank Pym. In the film it was revealed that Janet and Hank made up the super tandem of the Wasp and Ant-Man until she shrunk down too far and disappeared into the quantum realm. This caused Hank to cease being the Ant-Man and created a rift between him and his daughter.

It was revealed earlier this year that Janet van Dyne will appear in next year's Ant-Man and the Wasp with Michelle Pfeiffer in the role. It's entirely possible that Janet will only appear in flashback sequences but, considering the fact that Scott Lang managed to shrink down to the quantum realm and then return, this means it's not entirely out of the question for Janet to do the same.

Will Hope finally be reunited with her mother? Only time will tell for sure.

Captain Marvel will take place in the 1990s and feature Nick Fury

Nick Fury and Captain Marvel

Ever since Marvel Studios announced its Phase 3 slate of films, fans have wondered what would happen in Ant-Man and the Wasp and Captain Marvel, the two films set for release between Avengers: Infinity War and Avengers 4.

How exactly could the MCU have two films after Thanos' arrival that wouldn't focus entirely on the Mad Titan's exploits? The jury is still out on Ant-Man and the Wasp, but we now know that Captain Marvel will take place in the 1990s, long before not only Thanos' arrival but the formation of the Avengers entirely.

The film will center around Carol Danvers and her journey to becoming Captain Marvel. Kevin Feige has revealed on several occasions that she will be one of the more powerful characters to appear in the MCU thus far saying, "she would be off the charts compared to anyone that we’ve previously introduced in a film."

The film will also feature Nick Fury without his eye patch, and may just reveal how he lost his left eye in the first place.

Captain Marvel will introduce the Skrulls

The Skrulls are one of those unique properties that can be used on film by both Marvel Studios and 20th Century Fox (in the same way as Quicksilver and Scarlet Witch).

While specific Skrulls can't be used due to their connection to the Fantastic Four (whose film rights belong to 20th Century Fox), the species overall can be used in the MCU, and Marvel Studios plans to do just that.

Shrulls are extraterrestrial shapeshifters who debuted in 1962 and have had numerous run-ins with the Fantastic Four in addition to a prolonged war with the Kree (the alien race first introduced to the MCU in Guardians of the Galaxy).

The Skrulls' involvement in Captain Marvel makes perfect sense since it was Kree technology that first gave Carol Danvers her abilities in the comics. This origin is likely to be somewhat tweaked for the film adaptation, but the Skrulls will be involved nonetheless, which will add an interesting wrinkle to the MCU going forward.

It will be the end of an era

For as much as the MCU has changed over the last nine years, it has pretty much stayed the same. Yes, Tony Stark blew up all of his suits at the end of Iron Man 3, but he was right back in one in Avengers: Age of Ultron.

S.H.I.E.L.D. fell at the end of Captain America: The Winter Soldier, yet the Avengers have kept on avenging without it. Heck, Captain America even gave up his shield at the end of Civil War but you just know he'll be getting it back in Infinity War.

The point is that the MCU hasn't undergone any drastic changes since its inception, but all of that is guaranteed to change by the end of Phase 3. By then, Robert Downey Jr., Chris Evans, and Chris Hemsworth will have appeared in ten, nine, and eight MCU films, respectively.

These actors (and many others) will need to move on from the MCU eventually, and the end of Phase 3 is the opportune time. It will undoubtedly be the end of an era.

No future films will be named until its over

Guardians of the Galaxy Vol. 3 Logo by Rob Keyes

Marvel Studios has never been shy when it comes to releasing the titles of its future films. In 2012, the studio announced the titles of its slate of Phase 2 films. Then it did the same for Phase 3 in 2014.

This allowed the films to generate early buzz and build incredible levels of anticipation from audiences as the release dates neared, but it also somewhat spoiled the events of the films still to come. Obviously if Iron Man is set to appear in Age of Ultron, then he will survive the events of Iron Man 3.

This is still an issue today, as the release of the Infinity War trailer and posters have spoiled the fact that Thor and Hulk will survive through the end of Thor: Ragnarok.

Going forward, however, Marvel has decided to hold off on announcing more Phase 4 films until Phase 3 reaches its conclusion. The only films announced so far are Guardians of the Galaxy Vol. 3 and Spider-Man: Homecoming 2, and that's how it's going to stay.

Avengers 4 may be titled "Infinity Gauntlet"

Thanos kills half the universe in Infinity Gauntlet

As stated above, Marvel has been very careful not to allow its actors to reveal any spoilers about future MCU films. Zoe Saldana, however, may have done just that when she spoke with the BBC's Lizo Mzimba on the status of Infinity War and said, "We’re in the middle of it, I think that the Guardians just shot their part when it comes to Infinity War’s, like, the first part. And we all have to go back for Gauntlet later this year."

James Gunn has since said that Saldana misspoke, but if the fourth film is indeed Avengers: Infinity Gauntlet, then the film will likely borrow heavily from the comic storyline of the same name, which saw Thanos in possession of the Infinity Gauntlet and all six gems. T

he title, therefore, spoils the end of Infinity War by revealing that the Avengers will fail to stop Thanos in his quest for the stones, and that the Mad Titan will be in possession of all six by the film's end.

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Are you enjoying MCU's Phase 3 so far? What surprises do you think Marvel has in store for the rest of it? Let us know in the comments below.