If there is one theme running through Supergirl's entire existence, it's that people (mostly male) are reluctant to believe in her. She gets that sort of static from the general public of National City, from the media pundits fretting that her long-term ratings may not live up to the promise of her strong premiere, and she's certainly gotten it from the mostly male creators that have worked on her character over her long history. Many of them haven't seemed to know quite what the character should mean or to whom she should appeal.
As a result, Supergirl's publishing history is deeply, deeply weird, even by the standards of superhero comic books, which regularly pull stunts like having an evil Superboy punch all of spacetime into submission or turning the Flash into a puppet. How weird? This weird...
Here is Screen Rant's list of the 11 Weirdest Supergirl Stories
12 The time Superman told her about Kryptonian incest laws
It seems like everybody who talks about weird old comic books gets to 1962's Action Comics #291 sooner or later, but for once, everyone else is right. The story starts out innocent and kind of cute, as Supergirl watches Lois get nowhere with Superman and decides to find her cousin a more exciting girlfriend. After two disastrous time-traveling matchups involving Helen of Troy and the Legion of Super-Heroes, Superman figures out what she's up to and drops this bombshell:
"If I ever did marry, it would be to someone super and loveable like... you! We can't marry because we're cousins. Though cousins can marry in certain countries here on Earth, we're both from the planet Krypton, where the marriage of cousins was unlawful!"
You'd think his Kansas upbringing would be more of a sticking point for Supe than the law of his dead planet, but it's a lot more troubling that he's pretty much fine with Supergirl's third choice - basically Supergirl herself, about ten years older. It's true that a lot of men seek out women who remind them of their mothers, but this is still as creepy as Silver Age superhero comics got. Even Larry Niven's "Man of Steel, Woman of Kleenex" said on this general topic, "She can't mate with Superman because she's his first cousin. And only a cad would suggest differently."
11 The time she macked on a hot guy who was her own super-horse
No longer satisfied with Krypto the Superdog, Streaky the Supercat and Beppo the Supermonkey, Jerry Siegel and Curt Swan introduced Comet the Superhorse (Adventure Comics #293, 1962). Unlike those other super-animals, Comet had no connection with Krypton or Kryptonite, and wasn't even really an animal at all. He was a centaur who wished to be a man and was mistakenly transformed into a horse, then given various super-powers, including immortality and telepathy, as a consolation prize.
He explained this deal to Supergirl, who basically said "Too bad" and gave him a carrot, but soon thereafter he did become a man for a bit (Action Comics #301, 1962) and used that precious time to pose as a rodeo performer. One contrived series of events later, he and Supergirl were named "King and Queen of the Rodeo" and kissed for the cameras. Of course, he never told her a thing about his "secret identity." Because why would he.
But on the other hand, she had no trouble riding bareback in a miniskirt on a creature that she knew full well thought of himself as a man, so in this race to the bottom of depravity, Supergirl came out slightly ahead.
10 The time she fell for a super-woman disguised as a super-man
When not testing the limits of Kryptcest or playing fetishistic games with centaurs, Supergirl started to consider a more normal relationship with a fellow superhuman in 1969’s Adventure Comics #384. Using Superman's Fortress of Solitude computer as her own personal KDate, she located Volar, a superbeing on a planet of utterly subservient women and men so chauvinistic they made Barney Stinson look like Steve Trevor.
Supergirl found Volar attractive enough, but... oh, the headline's already given it away: As Kara would have learned instantly if either Superman or Volar believed in actually talking about important plot points without the use of visual aids, Volar was really a (presumably heterosexual) woman (both biologically and in how she identified).
To Supergirl's credit, her willingness to be a hero on Volar's world, despite its people's contempt for her, inspired Volar to do the same as herself, without a disguise. But Supergirl's vast range of powers didn't include heteroflexibility, and after seeing Volar as herself, she fled the planet in tears, which probably dampened Volar's feelings of empowerment a wee bit.
9 The time she saved the entire multiverse, which thanked her by writing her out of existence
Even Supergirl's best moments usually have a little tinge of weirdness to them. Crisis on Infinite Earths was kind of a mess of a story overall. But it did have more than a few affecting moments, and issue #7 (1985) had more than any other.
In it, Supergirl went up against a universe-destroying megalomaniac right after he beat the hell out of her cousin, throwing everything she had into protecting him and their adopted world, sacrificing her life even as she walked back the beliefs of a lifetime by swearing to kill her enemy. A moment's distraction allowed him to strike a final, fatal blow and escape.
Kara's sacrifice was powerfully written and beautifully drawn, especially by the standards of the day, but it was also just one twist in a bizarre, rambling tale that also involved an antimatter universe, five different Earths all skooshed together and, ultimately, a rewritten history with only one Earth, in which Kara simply had never existed and only a few refugees remembered she had ever lived. And by the way, the guy she was fighting, who presided over the antimatter universe? He was called "The Anti-Monitor" and no one seems to have meant it as a joke.
8 The time she was a blob of protoplasm and also Lana Lang and also the last survivor of a dying Earth
That "only one Earth" idea didn't last too long: cracks were already showing when a new Supergirl popped up in Superman Vol. 2, #21 (1988). She was from a pocket universe, which is like an alternate universe, but... smaller? Or something? Her real name was "Matrix," a shapeshifter with Lana Lang's DNA, which that world's heroic Lex Luthor had created in a world where Superboy had died early and the Phantom Zone villains had escaped to wreak havoc on the world.
They ultimately killed everyone on Matrix's Earth except for her and "our" Superman, who felt he had no choice but to kill them back. Most Superfans remember this story as the first time Superman really killed someone, so this is the reason anybody thought the climax of Man of Steel was a good idea.
Less well-remembered is the aftermath, wherein Superman took Matrix to the Kent farm and pressured his poor old parents into raising her, and then both he and Matrix went a little bonkers with PTSD, with Matrix assuming Clark's identity for a while and both of them, at different times, taking a little time-out in deep space on walkabout. And that's why anybody thought the beginning of Superman Returns was a good idea.
7 The time she shacked up with Lex Luthor
As Matrix returned to Earth, our Lex Luthor had hatched his most soap-operatic scheme ever: faking his death, then posing as his own illegitimate son in a cloned, younger body, even doing a hilarious Australian accent to throw off the rubes. It actually made sense for Supergirl to get interested in this nice young man, since he sorta reminded her of her universe's nice Luthor (Action Comics #677, 1992).
Superman smelled something kind of off about this situation, but his long hours saving planets, writing op-ed pieces and being dead for a few months didn't leave him a lot of time to marathon General Hospital. So he didn't catch on to Luthor's plan for a long, long time. During that stretch, we, the readers, got to "enjoy" the long con Lex worked on her and the implication that he was banging a red-and-blue-suited superbeing on a nightly basis. What this says about Lex's psychology, you can probably work out for yourself.
6 The time she became an angel
After that house of cards finally collapsed, Supergirl was a little adrift. You know how it is when you get out of a relationship with a controlling partner, especially when you're also a superhero and shapeshifter who can look like anyone on Earth. She needed a purpose. So in Supergirl #1 (1996), she merged with a dying teenage girl named Linda Danvers, because apparently that was one of her powers that she never got around to using before, and then started living Linda's life while using her powers to, among other things, track down the demon who killed Linda.
Along the way, she started manifesting angelic powers too, for reasons. A new version of Comet the Superhorse showed up, this one transgender as well as trans-species and also an angel.
Despite this ludicrously complicated setup, the series lasted a very healthy 80 issues and was probably Supergirl's most relatable run overall, and it's interesting to compare it to its near-contemporary Buffy the Vampire Slayer. Let's just say that Supergirl had a blond enemy-turned-friend-turned-lovesick-hanger-on some time before Buffy met Spike.
5 The time she was Superman's archenemy
No one seems to be quite sure where the Linda Danvers Supergirl is at this point (we last saw her in Hell, of all places), but not long after Supergirl's comic cancellation, a Supergirl from Krypton showed up (Superman/Batman #8, 2004) who was just straight-up the cousin of Superman. No angel powers, no shapeshifting, no unfortunate Luthor connections, no alternate-Earth shenanigans... just Kara Zor-El, the classic "Orginal Recipe" Supergirl from before things got messy. Except for the part where she might've been sent back to kill Superman.
Not that she remembered this at first, but eventually dark memories came back to her... sometimes showing her gleefully bloodthirsty about the prospect, sometimes showing her reluctant. It took the narrative a couple of years to make up its mind about this, but don't worry: Kara was always sent to Earth to protect Superman, and the distortion of her memories was a sign of Kryptonite poisoning. The moral of this story is, if you hear voices telling you to kill your family, you should see a doctor.
4 The time she was essentially super-Paris Hilton
Supergirl headlined another series from 2005-2011, but she was pretty hard to root for in the first 15 issues or so. It didn't help that the series seemed to change writers like ordinary people change underwear, and showed its teenage heroine in her underwear - or out of it - more consistently than it assigned her character traits.
At one point, she sold a Kryptonian invention to Batman for a cool million and got more interested in partying and clubbing than actually protecting the public. Millionaire, directionless, party girl, frequently buck naked, heiress to a famous name - the only way she could have been more Hilton-y is if she had gotten Maxwell Lord to produce a reality show starring her and Nicole Ritchie. Oh, and then there was her tendency to flirt with superheroes ten or twenty years her senior.
Later writers eventually rebuilt her as a somewhat likable character, one pang of conscience at a time, but it took some doing.
3 The time she went to live in the 30th century for the rest of her life
Over in the world of animated cartoons, Supergirl's problems were a lot simpler: a bad day for her on Justice League Unlimited would involve fighting an evil double or dealing with a catty colleague. But she still had the problem every version of Supergirl runs into sooner or later - being compared to her cousin. In one of the last JLU episodes, she and a few other Leaguers meet up with the Legion of Super-Heroes in the 3oth Century - and Kara decided to stay, since the far-flung future felt more like home to her, and there was no Superman here to be compared to.
Well, no living Superman, anyway. Just a thousand-year-old legend that was probably even more perfect than the actual Superman. Might not have thought that one all the way through, Kara.
Still, she also stayed because of her budding attraction to the Legion's Brainiac 5, and while B5 was another descendant of a maniacal supervillain like Lex Luthor II, he was neither secretly that same villain in a cloned body nor secretly a woman nor secretly a demon nor secretly Superman ready to tell us about Kryptonian incest loopholes, so by Supergirl standards, this qualifies as a solid life choice.
2 The time she was just Jimmy Olsen's imagination
The difficulty DC Comics creators had with the whole Supergirl concept was there right from the start. Even though her debut would kick off thousands of fan letters and there had been other successful "female version" characters, they were still hemming and hawing in 1958, one year before Supergirl actually debuted. So they decided on a test run.
In Superman #123, Jimmy Olsen got a hold of a totem that granted wishes, and much like Kara would years later, decided that his best pal needed a little matchmaking. So he wished a "Super-Girl" into existence, no relation to Superman, who could serve him as both a crimefighting and a romantic partner. The two mostly got in each other's way, but Super-Girl did save Superman from a Kryptonite trap.
On the other hand, she was pretty overconfident about her own ability to withstand K-radiation: it seemed she was slower to succumb to it, but, unlike Superman, couldn't just shake it off after getting away from the Kryptonite itself. Jimmy ended up having to mercy-wish her back out of existence, rather than watch her die a painful death from radiation poisoning.
But no worries! This was one of Superman's "imaginary stories," so it wasn't even as "real" as an in-canon Superman story. That version of Super-Girl was, like, triple imaginary. Just ignore her screams!
When they introduced comic book shows like Gotham, The Flash, and Arrow, lots of people were hoping they would stay true to the comics. So far, Supergirl is more or less blazing its own trail, and looking back at her history... that might be for the best.