Marvel has established itself as the preeminent superhero movie company, churning out hit after hit featuring their biggest characters. Whether it's in the Marvel Cinematic Universe proper, in Fox's X-Men movies or Sony's previous Spider-Man iterations, Marvel movies have ruled the box office with an iron fist. While the nonstop action and larger than life characters draw viewers in, it is the plots that keep them coming back. As movie-spanning plots play out, viewers get heavily invested, waiting on bated breath to find out what happens next in the Marvel saga. Unfortunately, Marvel has left plenty of dangling plot threads over the years, and it is highly unlikely that viewers will ever get answers to these burning questions.

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As the Marvel movie machine chugs along, plenty of seemingly important plots have been left in the dust. Characters have been dropped, events have been forgotten, and important plot points have been swept under the rug. For fans that get invested in Marvel movies, these lingering questions can prove maddening. Thankfully, CBR is here to dredge up all that fanboy anger all over again, as we take a look back at all the cliffhangers, unresolved plots, and forgotten characters that have graced Marvel movies over the years. These are the 15 Marvel movie plot points that will NEVER be resolved!

15 MYSTIQUE'S PLAN

X-Men Days Of Future Past Mystique Stryker

With the semi-recent soft reboot it experienced, Fox's X-Men movie franchise is still working to build a new X-Universe. While Logan reinvigorated the franchise, the film wasn't exactly interested in tying up any loose ends left dangling from previous movies. Case in point: the completely unaddressed ending to X-Men: Days Of Future Past that implied a big change to the X-Men world.

As the time travel-happy Days of Future Past comes to a close, Wolverine is pulled from the Potomac River by Colonel Stryker in 1973. But it is revealed that Stryker is actually Mystique in disguise. Does this mean Mystique killed Stryker? Did Mystique put Wolverine into the Weapon X program? Wolverine: Origins showed Wolverine joining Weapon X in 1975, a whole two years after the end of DOFP. Does this still come to pass, or has this event set in motion a new timeline? The ending left plenty of lingering questions, none of which will likely ever be answered.

14 WHAT BECAME OF UNCLE BEN'S KILLER?

Amazing-Spider Man Uncle Ben's Killer

Spider-Man 's kindly Uncle Ben was senselessly gunned down by a thief Peter had previously neglected to stop, teaching the hero that with great power, comes great responsibility. In  2012's The Amazing Spider-Man, Peter commits himself to hunting down his Uncle's killer... until he just kind of gives up.

After realizing that his negligence led to the death of his uncle, Peter uses a police scanner in hopes of receiving a lead on the whereabouts of the killer. But when the Lizard rears his scaly head, Spider-Man finds himself occupied fighting this new threat. And the hunt for Uncle Ben's killer is never mentioned again. As far as viewers know, Uncle Ben's killer continued to roam the streets of New York until the plug was pulled on the ASM franchise.

13 AGENT COULSON'S "DEATH"

Agent Coulson

S.H.I.E.L.D. Agent Phil Coulson played an integral part in the early days of the MCU, working as Nick Fury's right-hand man while Fury spearheaded the Avengers Initiative. Coulson would go on to become a fan favorite character, only for the Agent to catch a spear to the chest courtesy of Loki, dying on a S.H.I.E.L.D Helicarrier. Except he's now totally not dead, and his friends in the Avengers have no idea.

When Coulson appeared seemingly unscathed in Agents of S.H.I.E.L.D., fans were left wondering how he had managed to cheat death. Turns out, Coulson had been revived thanks to S.H.I.E.L.D.'s super-secret "Project T.A.H.I.T.I." Coulson has since gone on to lead a team of S.H.I.E.L.D. agents in many adventures, and has even graduated to head of S.H.I.E.L.D., but the Avengers still have no idea that Coulson isn't dead. Will he ever reveal himself to Tony Stark and the gang? Why hasn't he told his friends he's not dead yet? With the Avengers busy with their own stuff, and Coulson busy with S.H.I.E.L.D. business, it seems like this is a plot point that will never be resolved.

12 TONY STARK'S PTSD

Iron-Man-3-Stark

In the critically divisive Iron Man 3, billionaire playboy Tony Stark deals with the ramifications of surviving the alien attack on New York during the events of The Avengers. Stark struggles with PTSD from the harrowing experience, finding himself crippled with fear and anxiety. The Battle Of New York has seemingly left Tony Stark an entirely changed man. And then Tony's PTSD is never mentioned again.

After Iron Man 3, Stark returns to his jovial, devil-may-care ways, seemingly having no problem with his heroic duties. While Tony is seen discussing his feelings with Bruce Banner at the end of Iron Man 3, the scene provides no closure. Does Stark still struggle with these feelings? Is he medicated for his PTSD? Fans will never know, as this plot point has no chance of being addressed in a Marvel movie.

11 THE GENTLEMAN

Amazing Spider-Man 2 The Gentleman

The Amazing Spider-Man 2 ended on a hell of a cliffhanger -- with Spidey having saved the day, a mysterious shadowy figure visits Harry Osborn in jail, where he speaks of a "special team" he is forming. The man is seen passing an assortment of gadgets, referencing the likes of the Vulture and Doctor Octopus. All signs seemed to point towards the shadowy man gearing up to assemble the Sinister Six. And then the ASM franchise was shelved, leaving fans with plenty of questions.

A deleted post-credits scene showed the shadowy figure, identified in the credits as "The Gentleman," consulting with the frozen head of Norman Osborn. But did The Gentleman work for Osborn? Or was Osborn simply a part of his plan? How could The Gentleman seemingly teleport and move without making a noise? ASM2 gave plenty of tantalizing hints at what was to come, but with the end of the franchise, fans will never know what The Gentleman had up his sleeve.

10 HOW WAS THE BIFROST FIXED?

Thor Bifrost

The Bifrost Bridge serves as a crucial means of transportation for the inhabitants of Asgard; after all, this mystical bridge links all nine realms of the Norse cosmos, allowing Asgardians to travel anywhere in the universe. But during the events of 2011's Thor, our titular hero destroys the Bridge to save Asgard from an army of frost giants led by Loki. With the bridge destroyed, Thor, along with the rest of Asgard, is cut off from the universe. At least, that's the case until the bridge is miraculously fixed in a way that is never addressed.

By the events of Thor: The Dark World, the Bifrost has been impossibly fixed and the Asgardians are free to once again travel the cosmos. But who fixed it? How could someone fix a powerful tool such as the Bifrost Bridge so quickly? With Thor jetting off to space for Thor: Ragnarok, Marvel fans definitely shouldn't expect an answer to this lingering question.

9 WHAT BECAME OF BETTY ROSS?

Liv Tyler looking concerned as Betty Ross in The Incredible Hulk

Ever since Marvel swapped out Edward Norton for Mark Ruffalo, 2008's The Incredible Hulk has become the red headed stepchild of the MCU. The events of the film are never referenced, and characters such as The Abomination and Leonard Samson have faded into obscurity, never to return. But one of the most glaring omissions brought on by the shunning of Incredible Hulk is the fate of Bruce Banner's love interest, Betty Ross.

After all, Betty Ross was built up as being Bruce's main squeeze, with Betty proving to be one of the few people capable of calming Banner out of his Hulk state. But with sparks flying between Bruce and Natasha Romanoff, it would appear that Banner has moved on. But what happened to Betty? Is she still alive? Is she still trying to convince her father that the Hulk is one of the good guys? Much like Hulk himself, it would appear that Marvel has moved on from Ms. Ross, leaving her fate up in the air.

8 WHAT BECAME OF THE ABOMINATION?

Abomination from The Incredible Hulk

Speaking of The Incredible Hulk, the film introduced viewers to one of the Hulk's most iconic villains: The Abomination. Serving as a look at what the Hulk could be if he gave into his anger, a knock down, drag out fight between the two at the end of the movie pushed the Hulk to his absolute limits. In the end, the Abomination is defeated and sent to prison. But what became of Emil Blonsky?

The Marvel short The Consultant established that Blonsky remains in a specialized prison, but there are still so many questions. Does Blonsky remain in his Abomination form? Do the British Royal Marines know that one of their best soldiers remains locked up by S.H.I.E.L.D.? Was the Abominations existence revealed by Black Widow's S.H.I.E.L.D. leaks? With The Incredible Hulk being disavowed from the MCU, Hulk fans will likely never know the final fate of the Abomination.

7 IS THE RED SKULL REALLY DEAD?

Red-Skull-Hugo-Weaving

As the founder of the villainous HYDRA, Johann Schmidt, better known as the Red Skull, laid the groundwork for conflicts in the MCU for decades to come. During World War II, the twisted Nazi would cross paths with Captain America during his hunt for the Cosmic Cube, hoping to use the powerful artifact to conquer the world. In a climactic battle, Skull would lay hands on the Cube, which seemingly disintegrated him and flung him into the cosmos. But did Red Skull really die?

Skull was one of the preeminent experts on the mystical artifacts he hunted, so it seems unlikely that Skull would have died from something as silly as "accidentally touching a magic cube." Did the Cube simply teleport Skull somewhere else in the galaxy? No body was shown, so it is highly possible that Skull is biding his time, planning his revenge. But considering the current political climate, Marvel likely has no desire to revisit Nazis, so it seems highly unlikely that Marvel fans will ever get closure on the Red Skull.

6 THE "WESTCHESTER INCIDENT"

professor-x-logan-patrick-stewart

For a movie all about closure, Logan isn't very interested in providing answers. The fate of important characters are never addressed, the ending gave fans only a vague idea of what came next, and, most importantly, viewers are never explicitly told what the "Westchester Indicent" exactly is, despite the film making numerous references to the event.

Vague allusions are made to the event, but Logan never explicitly spells out what went down. Viewers know that Professor X lost control of his powers, and something tragic happened. But what exactly? Did Professor X kill the X-Men? What caused Professor X's meltdown? What became of the school? With Logan serving as a send-off for Hugh Jackman, the odds are good that fans will never know what the Westchester Incident exactly is.

5 BLACK WIDOW'S S.H.I.E.L.D. LEAKS

15. Black Widow

Natasha Romanoff, better known as Black Widow, has lived her entire life as a covert operative; as a result, she has learned to keep people at a distance and to keep her cards close to her chest. But during the events of Captain America: The Winter Soldier, Cap and his team discover that HYDRA have infiltrated S.H.I.E.L.D. and are planning to use the spy organization to enact a sinister plan. Faced with the choice of revealing the plot to the world, Widow opts to leak all of S.H.I.E.L.D.'s files, thus revealing HYDRA's plan, along with her own existence, to the world. And then... nothing.

In subsequent MCU films, the leak is never referenced. As S.H.I.E.L.D. likely held some of the biggest secrets in the world, the leaks of their files should have been huge. Did the Avengers learn anything from the leaks? With the leaks revealing Widow's existence, what does the public think about The Avengers running around with a known assassin? The event suggested big ramifications, but Marvel seems perfectly satisfied never addressing this plot line again.

4 WHAT BECAME OF SABERTOOTH?

Sabertooth

Over the years, there has been one hate-filled, sharp-awed constant in Wolverine's life: Sabretooth. The pair have fought alongside, and against, each other numerous times over the decades, and all signs seemed to point towards the rivals offing each other as an inevitability. But when Logan rolled around, Sabretooth's final fate was never addressed, a glaring omission for such an integral character to the Wolverine mythos.

In a deleted scene, Logan briefly discusses Sabretooth with a child, but it is never established what became of the villain. Did he die? Did Wolverine kill him? Is he still alive somewhere? Did Logan and Victor ever bury the hatchet, or just bury their claws in one another? Despite Sabretooth's importance in the story of Wolverine, fans will likely never get closure on Sabretooth's story.

3 WHAT HAPPENED TO SAMUEL STERNS?

Samuel Stearns begins to become The Leader in The Incredible Hulk

Bruce Banner considers The Hulk a curse; after all, it takes one slight annoyance to unleash the Green Goliath. So it makes sense that Bruce would seek help in ridding himself of his Hulk problem, and Banner believed he found a partner in Dr. Samuel Sterns. But when it came to light that Sterns had more insidious plans for Banner's gamma irradiated blood, he abandoned Sterns, and in an ensuing fight with Emil Blonsky, Sterns is doused in a sample of Banner's blood, causing a transformation.

It is suggested that Sterns would turn into the hyper intelligent villain known as The Leader, but Marvel's snubbing of The Incredible Hulk put an end to any chance of seeing what became of Sterns. A follow-up comic showed Sterns being taken into S.H.I.E.L.D. custody, but what happened next? Did Stern transform into The Leader? Is he still alive? Just like the rest of The Incredible Hulk's dangling plot lines, Stern's final fate will likely never be revealed.

2 THE INFINITY GAUNTLET AND ODIN'S TREASURE VAULT

Thanos and the Infinity Gauntlet

Thanos has loomed as an impeding foe to the MCU, biding his time in the far reaches of the galaxy. Armed with the Infinity Gauntlet, Thanos controls the Infinity Stones, giving him seemingly limitless power. But Thanos is far from the first owner of the Infinity Gauntlet; in fact, a blink-and-you'll-miss-it easter egg revealed that Odin possess the Infinity Gauntlet. So, how did Thanos come to possess the Infinity Gauntlet?

In 2011's Thor, the Infinity Gauntlet is shown on a pedestal in Odin's treasure room, yet Thanos later has the Gauntlet. Marvel Studios President Kevin Feige has explicitly said that the MCU has two Infinity Gauntlets, but this just raises more questions. How did Thanos and Odin acquire their Infinity Gauntlets? Why make two? Why not use Odin's Gauntlet to fight back against Thanos? As this issue arrises thanks to a glorified continuity error, don't expect the MCU to address this dangling plotline anytime soon.

1 WHO WAS THE REAL MANDARIN?

15 Times Marvel Studios Got The Avengers Wrong

Let's not mince words: Shane Black's Iron Man 3 had plenty of issues, ranging from a meandering plot to wasted characters. But no aspect of Iron Man 3 was more controversial than the revelation that Ben Kingsley's The Mandarin actually wasn't the real Mandarin; rather, he was a cowardly British actor named Trevor Slattery hired to portray the Mandarin by A.I.M. As Iron Man 3 ends, Slattery is taken into custody and the real Mandarin remains at large. But who exactly was the real Mandarin?

In the follow-up short film All Hail The King, Slattery is confronted in prison by a disciple of the real Mandarin, who accuses Slattery of "stealing" the Mandarin's name, and kidnaps the actor to bring him to the Mandarin. But viewers are never shown the true Mandarin. What does he look like? What is his plan? What does he intend to do with Slattery? With Iron Man 3 receiving such mixed reviews, and with Tony Stark having his hands full with Avengers business, fans shouldn't expect any Mandarin closure.

What other dangling plot threads would you like to see sewn up in the MCU? Let us know in the comments!