The Marvel Cinematic Universe is an unparalleled success, but it's still interesting to imagine what might have been given a few changes here or there. Marvel Comics has published a series of What If? issues for years, looking at the shape of the Marvel Universe given tweaks to major developments. These playful alternate realities tend to end in abject disaster, but nonetheless, it's always a thrill to see what might have been. The MCU is deep enough into its own shared story construction to begin a similar retroactive rewiring. From casting decisions to studio developments to in-story writing, what are the biggest "what ifs" of Marvel Studios' grand design?

RELATED: The 15 Worst Things To Happen To Women In The MCU

This isn't to say the MCU needs major changes. Obviously when you're the biggest show on earth, it's pretty easy to defend your decision-making. No, instead we're interested in analyzing how different the MCU could look today if several "near-misses" had come to fruition. Given all the backroom haggling and years of production that go into building the most intricate shared universe in movie history, it's still truly a wonder anything gets made, and made well at that. Without further ado, here are the ideas and decisions left on the cutting room floor that could have changed the MCU forever.

*Spoilers For The Entire MCU Follow*

18 RED SKULL RETURNS TO EARTH DURING AVENGERS

The thing about any "death"  that involves cosmic cubes and interdimensional portals is that it's going to lead to nearly unlimited theories that nobody is actually dead. This is the curious case of the Red Skull in the MCU, as the longtime Captain America foe, head of Hydra, and embodiment of pure Nazi-loving evil is somewhere out in space-time drifting along until his (we hope) shocking return.

Rumors stemming from an Avengers Red Skull toy indicate this return nearly happened during 2012's Avengers when Loki and the Chitauri ripped a giant wormhole open over New York. Screenwriter Zak Penn has suggested his work on early drafts of Avengers considered including the Skull, which would have shifted the course of the MCU. In addition to establishing a potential connection to Thanos, the third act reveal of the Skull could have overshadowed Loki's role as the primary antagonist in the film.

17 INHUMANS MOVIE

Logistically the inclusion of the 2018 Inhumans movie in the MCU slate could have led to all sorts of changes. Most positively, Inhumans never moves to ABC for the maligned TV miniseries currently denigrating Marvel's good name. The promise of a feature film also doesn't lead Agents of S.H.I.E.L.D. fans across the globe to collectively wonder why the actual hell the royal family wasn't included in the season two introduction of Inhumans on Earth.

Narratively, it's hard to see how Inhumans would have played in the post Avengers : Infinity War timeslot, and presumably that aided its departure. That said, who knows if Thor: Ragnarok would have as comfortably lifted "Asgard on a Ship" from the Secret Invasion era Inhumans if "Attilan on a Ship" was still available.

16 SPIDER-MAN & SONY

It's strange now to imagine the Marvel Cinematic Universe without Peter Parker, but that's exactly what we had for the first seven years. Admittedly, if Marvel Studios and Sony had never come to a deal, you'd lose an infinite amount of delight and charm via Spider-Man: Homecoming and Captain America: Civil War cameos, but the overarching plot of the MCU would largely continue unimpeded.

More interestingly to us, what if Marvel Studios and Sony had come to an arrangement on Spider-Man rights sooner? Joss Whedon reportedly wanted to include Spidey as a New Avenger in Avengers: Age of Ultron which would have introduced a completely different thread for the film to follow. Given the success of all things Spidey in the MCU, it's hard to wish this had played differently, but it certainly could have.

15 AGE OF ABOMINATION

Both Abomination and the all-too-briefly teased Leader are unfortunate losses to the depths of 2008's overshadowed Incredible Hulk. Despite a reference in the Marvel one-shot The Consultant, Tim Roth's portrayal of Hulk villain Emil Blonsky has yet to return anywhere in the MCU.

According to Roth, there were talks of Abomination returning to the Marvel landscape in the second Avengers film. Such an addition could have made for a supremely more menacing villain-set in Age of Ultron, with James Spader's already threatening Ultron enlisting the aid of one of the strongest baddies in the entire Marvel Universe. Breaking the Abomination out of prison would have also done a nice job connecting the shared universe, and indicating these villains aren't just tossed aside after their initial appearances in the cinematic franchise.

14 EDGAR WRIGHT'S ANT-MAN

Marvel Studios has started to overcome this reputation in recent years with more creator-hued work by Taika Waititi and James Gunn, but the production of Ant-Man came during a tumultuous time. Edgar Wright was seemingly driven off the project due to editorial interference, eliciting Director's Club support from Avengers: Age of Ultron director Joss Whedon (also soon to be dissatisfied).

Without casting too much shade on Peyton Reed's work off the bench (after all, Ant-Man is a serviceable origin story), it remains difficult to withhold pining for what might have been. Wright's unique style and voice have built serious affection, with works like Shaun of the Dead and Hot Fuzz developing passionate fans. Apart from film changes, we wonder the impact a Wright-led Ant-Man could have had for Paul Rudd's Scott Lang, with the possibility of a more feverishly beloved movie driving a greater role for the small-scale hero.

13 HELA IN THOR: THE DARK WORLD

Following her onscreen debut in Thor: Ragnarok (played by an eagerly evil Cate Blanchett), reports have circulated that Hela was close to debuting as the main villain of Thor: The Dark World. This bombshell revelation clearly would have shaken up the Thor trilogy. What would the impact have been on both The Dark World and Ragnarok with Hela in the MCU as early as 2013?

Although it feels like Ragnarok would fall apart without Hela's evil-sister appearance, it seems likely the switch could have very much helped Malekith. In fact, we're brimming with excitement at the thought of a Taika Waititi written Malekith getting the chaotic glory the dark elf deserves. By the same token, it's unlikely even Hela could have saved The Dark World's oddly basic villains from flat characterization and also-ran status next to Loki.

12 MARK MILLAR KILLING THE MANDARIN

In a strange intersection of high profile comic book creators and the MCU, the story goes that 2008's Iron Man initially intended to include the Mandarin as the primary villain. Jon Favreau's plans for the origin meant the leader of the 10 Rings would have come to life in a significantly expanded role bringing Tony Stark face to face with the quagmire of modern terrorism.

As he tells it, comics superstar Mark Millar (Kick-Ass, Old Man Logan, Ultimates) was the one who talked Favreau out of plans to include Mandarin right away, instead focusing on Jeff Bridges' Iron Monger. While this was originally intended to set up the Mandarin as the overarching villain behind the scenes, the directorial shift from Favreau to Shane Black for Iron Man 3 led to one of the most controversial twists in superhero cinema, and the absence of a true Mandarin to date.

11 JEFF GOLDBLUM AS A SENATOR IN CAPTAIN AMERICA

Marvel Studios head honcho Kevin Feige is on record as saying he always wanted Jeff Goldblum to appear in a Marvel movie, and it almost happened much earlier in the MCU timeline than Thor: Ragnarok. In fact, according to Feige, Goldblum was initially approached for the role of Senator Brandt in Captain America; The First Avenger.

In retrospect, this seems like a tremendous waste of the actor's idiosyncrasies, and fortunately Goldblum agreed, or was simply too busy. Instead, we got to enjoy Goldblum bringing all of his unabashed charm and humor to the role of Thor: Ragnarok's Grandmaster, a snazzily-dressed cosmic tyrant. Hindsight is of course 20/20, but it's genuinely difficult to picture Goldblum playing the relative straight-man in a World War Two period piece, especially compared to the hilarious energy he was able to bring to the lord of Sakaar.

10 PATTY JENKINS DIRECTING THOR: THE DARK WORLD

Before she was reinvigorating DC's cinematic landscape and bringing Wonder Woman to life for the character's first feature film, director Patty Jenkins was intended to direct Thor: The Dark World. Rumors vary as to the exact reason Jenkins left the project, but the director has remained professional in discussing the exit as "mutual." Nonetheless, Jenkins' departure from the project was enough to upset many, including Natalie Portman, who reportedly only appeared in the film without Jenkins due to contractual obligations.

If Jenkins leaving The Dark World was the move that had to happen to give us Wonder Woman, most comic book fans will appreciate the karma. That said, now that we've seen what Jenkins is capable of in superhero cinema, her Thor: The Dark World will remain an apocryphal gem lost to the MCU.

9 WHERE'S OUR BALDER AT

The absence of Balder the Brave, one of the leading Asgardian Gods from the comics, is one of the stranger omissions in the Marvel Cinematic Universe. Many fans presumed Balder would finally make his debut appearance in Thor: Ragnarok given that his death sets off Ragnarok in the comics, a move that actually makes even more sense when you consider Balder is Thor and Loki's half-brother. Nonetheless, a trilogy of Thor feature films has nary a mention of one of Asgard's finest.

Strangely, concept art for 2011's Thor directed by Kenneth Branagh reveals designs for Balder the Brave. When we consider the bit parts given to the likes of the Warriors Three or even Idris Elba's Heimdall, perhaps there has simply never been room enough for a character as worthy as Balder. That said, the Thor mythos is simply incomplete without him.

8 WASP IN THE AVENGERS

True to her legacy, Marvel's Wasp very nearly joined Joss Whedon's 2012 masterpiece as a founding Avenger. Whedon has gone on record a number of times describing early version of Avengers that heavily featured The Wasp, with Whedon ultimately declaring he couldn't find a way to fit Janet Van Dyne (or alternate alias) into the script. As a result, the MCU's first Wasp reveal took until 2015's Ant-Man (and even then, not until a post credits stinger (puns!)).

In addition to diversifying the Avengers roster gender dynamics, Wasp's inclusion with her comic book lineage would have shaken up the entire premise for Ant-Man. This seems far from unsolvable, though, as instead of Hank Pym's talented daughter, Evangeline Lilly could have simply continued her role as ex-romantic partner Janet Van Dyne.

7 NOVA, GUARDIAN OF THE GALAXY

Rumors abound surrounding the near appearance of Richard Rider (or Sam Alexander) as an Earth-born Nova in Guardians of the Galaxy. As we know, the Nova Corps of Xandar played a prominent role in the film, and John C. Reilly's Rhomann Dey suggested a potential connection to Richard Rider Nova lore. Rider never appears in the film, though, despite the reveal of concept art of a Nova helmet resembling Rider's from the comics.

Nova's inclusion would have greatly enhanced the depth and star-power of the Marvel cosmic landscape. It's easy to see why James Gunn and company would have felt the script was already plenty crowded with character introductions. For fans who fell in love with the character during the run from Annihilation through Thanos Imperative, Marvel cosmic just doesn't feel complete without Nova.

6 CAROL DANVERS IN AGE OF ULTRON

Carol Danvers, the Marvel Universe's current Captain Marvel, was so close to an appearance in Avengers: Age of Ultron Joss Whedon even shot FX footage of the longtime Avenger in flight. Ultimately Kevin Feige and Marvel Studios concluded introducing Captain Marvel fully established as a costumed hero would be too jarring to unfamiliar audiences.

Captain Marvel's addition to the Avengers in the fight against Ultron could have thrown a wrinkle into her currently slated solo film for 2019. The upcoming Captain Marvel is said to take place in the '90s, raising a number of questions about how the character will fit chronologically alongside the Avengers of the late '00s. We see some potential optimism in the delay, as it could give Captain Marvel more of a leadership role for a new look Avengers coming out of Infinity War.

5 YONDU & NEBULA KO'D

Initial drafts of James Gunn's Guardians of the Galaxy script nearly led to the deaths of Yondu and Nebula. Actress Karen Gillan has stated Nebula was originally intended to die in the first Guardians of the Galaxy, while Yondu nearly met an early demise opening the trojan-infinity stone and finding one of Rocket Raccoon's many, many, many explosives.

Obviously, both of these tragic fates were written out of the end product, and both characters were given significantly expanded roles in Guardians of the Galaxy Vol. 2. Nebula's development in Vol. 2 propels Gamora's connection to her sister and to their childhood at the hands of Thanos. Even more importantly, Yondu is the emotional epicenter of Vol. 2, with his actual death generating the movie's surprise gut punch.

4 ARNIM ZOLA IN ANT-MAN

Although he appears to meet his demise in the destruction of his Commodore-64 hideout, comic book readers know that Captain America: The Winter Soldier's Arnim Zola is never really dead, only transported to a new robotic host. Zola's survival was nearly confirmed in 2015's Ant-Man, as concept art of a modernized classic Zola look suggests.

As we know now, Arnim Zola, as portrayed by Toby Jones, was nowhere to be found in Ant-Man. The longtime agent of Hydra was allegedly set to make an appearance in the flashbacks to the youthful S.H.I.E.L.D. plotting of Hank Pym and Howard Stark, although given the speculative nature of this reveal, Zola certainly could have played a greater role in the present day as well. It wasn't to be, but we're still waiting for the return of Zola someday soon.

3 EGO FOR NEGASONIC TEENAGE WARHEAD

It's not quite Sam Bowie for Michael Jordan, but Ego the Living Planet traded for the powerset of Negasonic Teenage Warhead may well be the strangest comic book movie transaction we'll ever see. As the reports go, Fox conceded the film rights to Ego the Living Planet, aka Kurt Russel's villain from Guardians of the Galaxy Vol. 2, in exchange for overhauling the mutant powers of Deadpool's grumpy Negasonic Teenage Warhead.

Amazingly, James Gunn confirmed his plans for Peter Quill's father always involved Ego the Living Planet, thinking Marvel Studios simply had the rights to the cosmic powerhouse. Gunn claims he had no backup in mind if the trade with Fox fell through, making this one of the more potent What Ifs in MCU lore. Who would Marvel have dropped into the role of Star-Lord's father without Ego? Somewhere in Hollywood, Simon Williams is getting his agent on the phone.

2 BETA RAY BILL INSTEAD OF HULK

Very early reports of plans for adapting Planet Hulk storylines as the third film in the Thor trilogy included rumors that Beta Ray Bill could take the Hulk's place as the Grandmaster's champion. This would have introduced the worthy Korbinite, and given him a sensible connection to the world of Thor and Asgard. Ultimately, this role was whittled down to a very slight cameo that was cut from final versions of the film.

The inclusion of Beta Ray Bill would have been a joyous sight for Walt Simonson Thor fans everywhere, but admittedly it would have taken away a great deal from the light "Planet Hulk" inspiration in the movie. Sure, we'd never say no to the appearance of the brawling totally-not-a-horse later on down in the MCU, but we can agree Thor: Ragnarok wasn't quite the right time.

1 GALACTUS & SILVER SURFER TRADE FOR DAREDEVIL

As much as we love the MCU's charge into Netflix series with Daredevil, it's not hard to see why Kevin Feige reportedly sought to trade the rights to Daredevil for Galactus and the Silver Surfer. It's the kind of fantasy trade your league would veto as being woefully unfair to Fox, and despite their unfathomable efforts to turn Galactus into a sentient gas cloud, Fox inevitably must have agreed.

While Marvel's binge-watching clout would have certainly dissipated, the addition of both Galactus and Norrin Radd to the MCU would be one of the best things that could happen. It's mildly difficult to approve of a giant purple helmet wearing OG shouting "I HUNGER!" without the Fantastic Four around, but let's not pretend this isn't a job the Avengers couldn't handle. Comic fans don't have to look further than Ultimate: Cataclysm to see how epic this might have been.

Which of these changes would've been the biggest? Let us know in the comments!