The 15 Most Buck Wild Supergirl Fan Theories (That Actually Make Sense)

DC Comics finally stuck the atypical superhero landing when they decided to put their infamous characters on the small screen. Supergirl, Arrow, and The Flash have been massively successful especially with their recent crossover episodes, which often includes DC’s Legends of Tomorrow. And while Gal Gadot surpassed expectations in her role as Wonder Woman when it hit theaters last year, Melissa Benoist had already been given high praise on her role as Supergirl in the self-titled CW show.

With millions of views each season, it’s clear that the Supergirl fanbase isn’t going anywhere. Supergirl is in its third season, and already we’ve seen a Kryptonian takeover, a LuthorCorp scandal, and even heartbreak. The drama never ends, and fans can’t get enough of the possibilities that could come of this show. And with these possibilities comes eager theories from fans. Whether it’s based on potential plotlines derived from the comic series, or speculation from the ongoing season, fans never shy away from a good superhero theory. The third season is in a brief hiatus until its return in April, so while we wait to see what happens, let’s discuss the 20 most buck wild Supergirl fan theories (that actually make sense).


While it seems unlikely that this season’s main antagonist could turn into a superhero, fans are speculating what will happen to Sam if Reign sees the end of her tyrannous days. While Sam’s alter ego terrorizes National City, fans have speculated that she will ultimately join Supergirl and the rest of the superheroes in a final showdown where Reign loses her possessive control. In fact, some are holding out hope that she will become Superwoman.

Before you discredit this theory, let’s look at the signs. Sam has a daughter and she’s made it clear that Ruby is a priority. Some fans think that Sam will overcome Reign for Ruby. Then, there’s the recent episode where Lena Luthor says she knows what’s wrong with Sam and that she’s going to help her. In one comic series, Superwoman (who is actually Lois Lane) gets her powers through an experiment conducted by LuthorCorp.


This “mind-blowing” theory comes from Reddit user Draxon123 after an eventful night of binge-watching Arrowverse shows. We know that the city of Gotham exists within Supergirl’s realm of knowledge since it was mentioned in the second season. Batman was also hinted at in Supergirl when Kara says her cousin used to work with a vigilante.

It’s possible that the events happening in the show Gotham is what took place while Kara was stuck in the Phantom Zone. This Reddit user was quick to pick up on the mention that a character can exist simultaneously in two different universes as well. So the fact that characters, such as Firefly, have appeared in both shows could simply just be the work of the multiverse, which we see a lot in the Arrowverse.


It seems impossible that Sam will leave National City forever after the end of the third season. She has become a staple in the close group of friends that Kara has, and fans don’t think that Sam having a lethal alter ego is enough to banish the character altogether. Although the Legion has already mentioned that Reign simply “leaves”, this action that is a little too vague for theorizing fans.

Instead, fans have been quick to propose that Sam will be able to control Reign, and possibly aid Supergirl with future dilemmas. Further still, fans wonder if Imra and the Legion of Superheroes will take Reign back to the 25th century with them after they learn what will destroy, or at least control, Reign’s abilities.


Back in 2016, there was a rumor that Supernatural will cross over into the CW’s Arrowverse. Stephen Amell, who plays Oliver Queen, inadvertently started this rumor when he expressed an interest in making an appearance on the show. He addressed the rumor at Salt Lake Comic Con last year, admitting that the cross over wouldn’t make sense since they are two separate universes. But with the DCU’s multiverse history (along with the fact that it is TV, after all), he would still love the possibility to transpire.

Supergirl and Supernatural are both run on the CW, so while the relationship between the Winchesters and a character in the DCU such as Supergirl would certainly be strange, fans have expressed their interested in seeing how the Arrowverse would respond to demons and vampires.


This seems a little harder to conceive since there are two different actors that play Superman. Tyler Hoechlin plays the Kryptonian in Supergirl while Tom Welling played the famed role on Smallville. However, the notion of multiverses makes the DCU possibilities limitless. However, instead of Smallville taking place in an alternate reality, one fan theory surmises that Smallville is a parallel Earth due to their many similarities. For example, Clark Kent is friends with Lex Luthor in Smallville, while Kara is friends with Lena Luthor in Supergirl. Both superheroes also cross paths with Green Arrow and the Flash, and Martian Manhunter plays a mentor to both superheroes.

Reddit user, Animation_Bat stated, “I think it’ll be a missed opportunity if Barry Allen doesn’t accidentally “run” into the Earth from Smallville.” This is exactly what happened in the first crossover episode “Star-Crossed”, when Barry happens to run across Supergirl!


At the end of season two of Supergirl, audiences emphasized with Kara’s heartbreak when Mon-El had to leave Earth. Thankfully, we saw the return of Supergirl’s love interest when he returned -- from the future -- with a wife. Mon-El revealed that he was married to Imra Ardeen (aka Saturn Girl). Karamel shippers felt destroyed by this new development, which is why one fan theory suggests that maybe Mon-El isn’t really married.

A lot of this theory stems from social media responses made by Amy Jackson, who plays Irma. When fans expressed their feelings for the marriage, Jackson coaxed them by stating there is “more to the story.” In the comics, Saturn Girl has psychic and telepathic powers, which is why a Reddit user believes that Imra is brainwashing Mon-El into thinking they’re married. Imra’s motive isn’t clear, but this may be Imra’s way to get close to Supergirl.


Some fans remain skeptical of this theory mostly because they don’t see the writers and the CW going to such harsh extremes. It’s also already known that Supergirl will survive the attack of the Worldkillers (because how else would the show go on without Kara Danvers?). However, there is a possibility that Reign could still destroy -- or kill -- something within Kara.

If the theory that Kara is a Worldkiller turns out to be true, perhaps Sam will be able to finally control Reign and use her powers to actually save Supergirl. After all, the comics state that only another Worldkiller can kill another. So it seems to stand to reason that if Kara is a Worldkiller, then Reign will ultimately “kill” Supergirl to get rid of the mutant part of Kara that is a Worldkiller.


It seems inevitable to fans that Kara and Mon-El will end up back together. Whether this is because Imra is manipulating Mon-El or because, as we recently learned, Mon-El may still be in love with Kara, fans don’t see Imra lasting past season three. One fan theory suggests that Imra will ultimately die in the battle against the Worldkillers. This obviously would leave room for Mon-El and Supergirl to get back together. It also eliminates Imra as an antagonist since so far, we haven’t seen any signs that she has malicious motives. And Imra’s death allows her to die a hero.

This also seems to be a safe bet since this scenario has happened in other CW shows, like when Felicity’s boyfriend died in Arrow. This ultimately left room for her and Oliver to rekindle their relationship, which is what fans are hoping for in Supergirl.


Alex’s breakup with her fiancé Maggie was a huge turning point for her character in the second season. The two broke up when Maggie revealed she didn’t want kids, an issue that Alex couldn’t compromise with. Since then, Supergirl has intensely focused on Alex’s character development, and one fan theorized that the reason for this could be because Alex is going to adopt Ruby.

Alex’s want to be a mother could have been built up to lead to this moment. Throughout season three, we have seen Ruby’s mother, Sam, struggle with the power of Reign. In one episode, we see Alex jump at the opportunity to watch over Ruby while Sam was out of town. And in a recent episode, we see Ruby being left at an ice skating rink when Sam’s Reign alter ego takes over. The events seem to be leading up to this theory actually coming true.


We already know this theory is coming to a realization with Supergirl’s latest episodes revealing a potential second Worldkiller. The Worldkillers in Supergirl are artificial humans previously constructed on Krypton to be used as weapons. Reign is the first in the lineup to show up in National City, and now we have her potential teammate, Julia Freeman. Also known as Purity, we see her meet with Reign in the latest episode, which seems to be a foreshadowing event that is close to what happens in the comics.

In The New 52’s Supergirl #5 Reign makes her first appearance, and is followed up with five more Worldkillers. With a second Worldkiller being introduced, will we see the full team come together by the end of the season?


In the final episode before Supergirl’s hiatus, Irma told Mon-El that it was time for her to explain the real reason they returned to National City. It always did seem too convenient that they ended up right back where Mon-El left off. Irma revealed this right after Mon-El tells her that he may still love Kara. If it is this bit of information that prompted Irma to tell Mon-El the real mission, fans have wondered if Supergirl is the reason for this mission.

One fan has concluded that since we know the Legion came from the 25th due to a cataclysmic event of Earth, that Supergirl wasn’t able to defeat the Worldkillers on her own (either that or Supergirl becomes a Worldkiller). They are coming to the 21st century to help Supergirl take on Reign, Purity, and Pestilence because in another timeline, Kara dies.


The Luthers are well known in the DC Universe for having ulterior motives. That’s why this theory that Lena will turn evil is a cinch. We have already been told that Lena will have "a surprising connection to Reign", and the history behind the Luthors certainly makes this theory plausible.

Showrunner Jessica Queller even confirmed, "She's a ticking time-bomb,” when referring the Lena’s character. Supergirl’s other showrunner, Robert Rovner, also added, "It's an interesting journey to be able to take her on. Will that one very bad day, or one very bad choice, tip her over the edge?" Fans seem to think so. There have been countless circumstances where Lena’s character has been called into question. In the third season, she teamed up with her evil mother, Lillian Luthor, to take down Morgan Edge, the twisted businessman in National City. Lena also admits to almost killing Edge before this.


True fans of the DCU never miss a thing. Reddit user, meagancarter4, came up with the theory that Superman already met Mon-El despite their supposed first meeting in season two. She discussed that since the Legion flight ring was already mentioned in season one, it must mean that Superman had already been to the future in order to obtain the ring. And since Mon-El discovered the Legion, it means that Superman met Mon-El in the future.

However, when they meet in season two, Superman has to pretend he hasn’t met him yet since Mon-El wouldn’t remember him. Superman is also associated with having created the Legion from 2008’s Action Comics story arc. So the two would have to have known each other fairly well. They even become best friends in the comics.


Fans are hoping to see the full team of Worldkillers take part in this season of Supergirl. In the comics, there were five total antagonists, each of them possessing their own unique alien powers. We know there will be at least three this season: Reign, Purity, and Pestilence. And somehow, fans have been able to come up with the theory that the third Worldkiller is Supergirl herself.

Reddit user, Daffydunk, speculated that Kara’s mother, Alura, is the creator of the Worldkillers. The CW recently cast Alura, hinting that her mother will make a comeback in the show. Her theory is that Alura turned on her team and banished them from Fort Rozz. “But most importantly she smuggled the first Worldkiller away from them to raise as her own daughter.” Jindah had also previously told Supergirl that uncertainty will be her doom, hinting that Kara may have a dark side.


This theory blew up after Supergirl (Melissa Benoist) starred in a promotional teaser for DC’s Wonder Woman film last year. The shot showed Supergirl wearing a pair a very familiar boots, to which she told her adversary, “You like? I borrowed them from a friend.”

It’s widely recognized that any DC (or Marvel, for that matter) televised characters are in a completely different universe than those you see in the DCEU. Clearly, as Ezra Miller plays The Flash in DC’s recent Justice League film while Grant Gustin still portrays Barry Allen on the CW series, a crossover with Melissa Benoist and Gal Gadot is likely to never happen. However, this little clip had fans practically begging for an introduction of the glorious Wonder Woman. And who knows, maybe it will be Gal Gadot who makes an appearance.

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