Arguably one of the purest heroes in Marvel’s endless roster of superpowered characters, Captain America has become firmly synonymous with freedom, unity and courage over the course of his 76-year history, with the Star-Spangled Avenger representing the very best of humanity. In fact, Captain America has become such a beloved character that he’s often the center of some of Marvel’s most heated controversies. With different readers having a varying opinion of what Cap symbolises to them, any changes to the character, no matter how temporary, are often met with heavy criticism.

RELATED: 8 Captain Americas Better Than Steve Rogers (And 7 Who Couldn’t Handle It)

Take Cap’s villainous turn in "Secret Empire", for instance, which did not go over well with fans of the character whatsoever. This is a problem for comic book writers, who need to come up with fresh, innovative stories for their characters while retaining a certain sense of status quo -- and is the reason alternate universes are such a widely used tool in comics. Enabling writers to explore bizarre hypotheticals, unique takes on popular characters and interesting, uncanonical stories, these universes are home to some of the strangest and most engaging content in the business -- and we’re here to take a look at 15 of the craziest versions of Captain America spread throughout the multiverse.

15 UNION CAP

Union Cap

Taking several iconic characters and beats from Captain America’s colorful history and reshuffling them in an interesting way, What if… Captain America Fought in the Civil War? provides a weird and wonderful take on Steve Rogers’ origin story. Following Rogers as he fights for the Union under his leader Bucky Barnes -- who unbeknownst to Steve will eventually become the malevolent White Skull -- Rogers abandons his post after Barnes orders the murder of several innocent civilians.

After Barnes shoots the fleeing soldier, Steve is found by none other than Sam Wilson, who delivers him to a nearby Native American reservation. There, the tribe’s mystically-trained chief performs a ritual that grants Cap his powers and a powerful shield that can transform into an eagle. Cap uses them to prematurely end the Civil War, but a new war is waged between Cap and White Skull.

14 PRESIDENT RED SKULL

Captain America Red Skull

With a penchant for taking the most beloved characters in the Marvel Universe and defiling them in the most unimaginable ways, Mark Millar has been the architect behind several of Marvel’s most controversial stories, with "Old Man Logan" perhaps standing as his crowning achievement.

While Millar’s incestuous, redneck version of the Hulk gets a lot of attention, Red Skull’s role in the story is also deeply unsettling. Having fought and defeated Captain America, Red Skull proceeds to kill his nemesis by forcing his thumbs into Cap’s eye sockets, before taking his costume for his own. Claiming the White House as his territory soon after, Red Skull declares himself the new President of the United States, all the while donning Cap’s iconic outfit -- with this new, twisted version of Captain America serving as a grim symbol of a true dystopia.

13 IRON CAP

Written by celebrated writer J. Michael Straczynski, Bullet Points explores an alternate reality where Dr. Abraham Erskine -- the scientist responsible for Captain America’s creation -- is killed before he can administer the Super Soldier Serum to Steve Rogers.

As a result of the project’s failure, Steve instead signs up for the “Iron Man project”, which sees Captain America fuse himself inside a primitive version of the original Iron Man armor. Unable to disconnect from the suit without dying, Cap willingly sacrifices any semblance of a normal life to assist in the United States’ war efforts, going on to win several campaigns against the Germans. Erskine’s death doesn’t just affect Steve Rogers however, and has a knock-on effect throughout the Marvel Universe that results in Peter Parker becoming the Incredible Hulk -- who kills Steve when he attempts to subdue the rampaging creature.

12 ZOMBIE CAP

Zombie Cap

One of the more famous alternate realities in Marvel Comics, Marvel Zombies has returned several times, with each story being crazier than the last; taking the characters you love and turning them into something much more sinister and grotesque. Referred to as Colonel America in this universe due to his higher rank (he even served a term as president), Cap is infected with the zombie virus along with his fellow Avengers when an infected Sentry attacks the group.

Consumed by his newfound hunger, Cap devours countless heroes and villains, leaving the world in ruins -- but is eventually killed by Red Skull in a dispute over Galactus’ remains. Things get even more insane however, when Cap’s brains are recovered 40 years later. Transplanted into the zombified corpse of Black Panther’s son, T’Channa, Cap leads the charge in a battle against the Hulk and his group of rampaging Zombie Galacti.

11 HYDRA CAP

Hydra Cap

In one of the most controversial comic book twists in recent years, it’s revealed in Captain America: Steve Rogers #1 that Cap is in fact a sleeper agent for Hydra -- and has been all along. Angering pretty much everyone in the comic book community, the storyline took a painfully long time to provide any answers at all, finally explaining the somewhat gimmicky storyline in the pages of Secret Empire.

It’s probably no surprise that the reasons behind Cap’s turn to the dark side ended up being needlessly convoluted, and involved Kobik -- a physical manifestation of the Cosmic Cube created by S.H.I.E.L.D. -- rewriting Cap’s history in league with Red Skull. Kobik eventually sees the error of her ways however, and helps the true Captain America defeat his evil alter-ego, restoring Earth-616’s original history.

10 GLADIATOR CAP

Captain America Exiles

Following a group of powerful heroes plucked from across the Marvel Multiverse, the popular Exiles series sees the titular team travel across space and time, fixing “hiccups” that threaten to unravel reality itself -- much like the “aberrations” seen in Legends of Tomorrow.

In one of the series’ featured realities, the Skrulls have conquered Earth, enslaving the planet and its superpowered beings in the process. Forcing the heroes to duke it out in gladiatorial combat, Captain America swiftly rises to the top of their ranks, gaining the Skrulls’ respect through his unmatched combat skills. His winning streak soon comes to an end however, when Mimic, infuriated by Captain America’s willingness to serve the Skrulls, swiftly defeats him with a newfound ability -- Cyclops’ optic blasts.

9 REVOLUTIONARY ROGERS

RevolutionaryRogers

Believe it or not, Steve Rogers wasn’t the first person to take up the mantle of Captain America. What’s even stranger though, is that the first person to do so also happens to be Steve Rogers’ ancestor, Steven Rogers. A Patriot captain in the Revolutionary War, Steven Rogers donned a more period-appropriate version of Cap’s star-spangled attire, and managed to put a stop to the Loyalist William Taurey, who planned to inform Great Britain of the Patriots’ plans.

In classic comic book fashion, it also turned out that Taurey had ulterior motives, hoping to solidify the power of an evil organization known as the Elite, before he was killed in a duel with the Colonial Captain America. Naturally this causes trouble for modern day Cap, who comes to blows with William Taurey’s equally evil descendent -- who’s seeking vengeance against Cap and his bloodline for their past deeds.

8 COLD WAR CAP

What if… Captain America Were Revived Today featured two polar opposite versions of Captain America: one who remained frozen in the ice after WWII and a brainwashed replacement with a volatile, authoritarian attitude. After the impostor is released into the public eye by a shadowy individual, he slowly uses his image as the embodiment of American values to influence the country’s citizens, convincing them that any form of protest or demonstration is dangerous and un-American.

Eventually, the brainwashed Cap begins to respond to such activities with brute force, violently shutting down any public criticisms of the US, all while endorsing certain unsavory candidates for the US senate. Fortunately, the real Captain America is unfrozen at this time, and engages in a brutal slugfest with his shady counterpart, coming out on top and winning the public back to his side with a rousing speech on what freedom really means.

7 THE FIRST APE-VENGER

Captain America Ape

As if an ape version of Captain America – as well as a whole Avengers team -- wasn’t weird enough, it’s eventually revealed in Marvel Apes that Captain America, leader of the Ape-vengers, is actually the diabolical Baron Blood donning an elaborate disguise. Plotting to invade Earth-616 to feed on its citizens, Baron Blood is eventually stopped by the real Captain America, who’s discovered and subsequently unfrozen by several other heroes.

As it turns out however, this version of Captain America is almost as messed up as his former impersonator, displaying surprisingly vicious tendencies as well as poor judgment. Showing no mercy whatsoever -- even to his loyal teammates -- Captain America is perfectly fine with executing anyone who defies his will, no matter how minor the infraction. Perhaps the Ape-vengers were better off with Baron Blood after all.

6 ROJHAZ

Rojhaz

Taking place in a Universe where the Purple Man has conquered the world and slaughtered its heroes, Neil Gaiman’s Marvel 1602 sees the villain transport Earth’s last remaining hero -- Captain America -- back in time to 1602, fearing that Cap may be hailed as a martyr in death. Upon his arrival in the Elizabethan era, an amnesiac Captain America is taken in by a Native American tribe, and soon becomes the bodyguard of Virginia Dare -- an infant member of the Roanoke Colony.

Cap’s presence in this timeline does more harm than good however, and several versions of Marvel’s heroes begin to materialize centuries before they’re supposed to, threatening to tear apart the fabric of reality itself. Luckily, several of 1602’s heroes, including Doctor Strange and Nick Fury, manage to trace the anomalous behavior back to Cap, and send him back to his original timeline.

5 AGE OF X CAP

Age of X Cap

Set in a dystopian future where the mutant population has been dramatically cut down by anti-mutant legislation, Age of X’s version of Captain America leads a group of so-called “Avengers” consisting of Iron Man, Invisible Woman, Ghost Rider, Jessica Drew and Hulk -- whose job it is to hunt down and kill mutants in hiding.

After storming the mutant stronghold Fortress X, Cap shoots and kills Mystique, and is horrified to discover she was merely protecting a group of innocent mutant children. This forces Cap and the Avengers to re-evaluate their stance in the war against mutants, turning on their leaders and fighting for the mutants instead. In response to their betrayal, General Frank Castle sends in a furious Hulk to detonate a biological bomb, but Cap ultimately gives his life to put foil his plans.

4 EARTH X CAP

Earth X Cap

Initially intended to depict the dark future of Earth-616, Earth X’s post-apocalyptic landscape became its own universe due to the sheer amount of canon-altering in the series. Following the death of the Avengers, the election of Norman Osborn as president and the revelation of a giant Celestial egg embedded in the center of the Earth, the planet is hardly in the best state.

The rapidly unfolding events have taken a toll on Captain America, who’s a much more beaten down version of the character than readers are used to. Sporting some nasty facial scars and a shaved head, Cap looks ready to attend a Fourth of July toga party, draped in a tattered American flag and wielding his trademark shield. Despite his advanced age and downtrodden attitude, Cap still manages to take out the child dictator Skull and free his friends, keeping the Earth alive to fight another day.

3 AVENGING ANGEL CAP

Captain America Angel X

Universe X -- the sequel to the popular series Earth X -- sees a weary Captain America protect a reincarnated Mar-Vell in an effort to combat the forthcoming threat from the aptly named Realm of the Dead. Killed by the Dead’s forces, the deceased Captain America is transported to Paradise, which is a realm created by Mar-Vell in the follow up to Universe X, titled Paradise X.

During the storyline, Mar-Vell decides to transform Cap into an angelic entity to help shepherd the souls of the dead to Mar-Vell’s Paradise. This version of the character bears very little resemblance to the traditional Cap that we all know and love, with his bald, battle-hardened Earth X aesthetic gaining bright blue skin and an impressive set of wings to match.

2 CAPTAIN AVALON

Captain Avalon

Coming out in the early '00s when Marvel was facing significant financial issues, the three-issue limited series Avataars: Covenant of the Shield unfortunately didn’t run for its intended 12 issues, and explored a fantasy version of the Marvel Universe created by the Shaper of Worlds as an experiment.

Called Eurth, the planet contained several alternate versions of Marvel’s heroes, focusing primarily on Captain Avalon -- this universe’s equivalent of Captain America -- in his quest to rescue his son from the clutches of the sinister Dreadlord. Assisted by an Avengers-like group referred to as the Champions of the Realm, Captain Avalon rides into battle with his legendary sword Excelsior and a redesign of his trusty shield, as well as a chunky set of armor, flowing blue cloak and a winged helmet.

1 SUPER-SOLDIER

Super-Soldier

Published by Amalgam Comics -- an imprint shared by both Marvel and DC in the late '90s -- the Amalgam Universe featured characters that were fusions of Marvel and DC’s most popular heroes. One of the more memorable characters in this universe was Super-Soldier -- a combination of Captain America and Superman. Granted his powers through a formula created from the genetics of a deceased alien, Clark Kent is exposed to the serum after signing up for the Super Soldier program.

With powers similar to those of Superman -- including superhuman strength, flight and vision, Super-Soldier dons a costume resembling Captain America’s, complete with a shield in the shape of Superman’s “S”. Among his foes was Green Skull, an amalgamation of Lex Luthor and Red Skull who eventually got the better of Super-Soldier by injecting him with Green K, causing his powers to fade over time.

Did we miss any of your favorite versions of Captain America? Let us know in the comments below!