Warning: SPOILERS ahead for Supergirl season 1

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Having only just wrapped its first season, CBS' Supergirl has already earned a passionate fanbase and an equally numerous cadre of detractors, with fans divided over its unique mix of soapy working-girl melodrama, Millennial rom-com hijinks and candy-colored superheroics. Yet audiences seem to have embraced Melissa Benoist's plucky interpretation of the Girl of Steel, and a second season order is widely regarded as a likely next step.

But the promise of a new season raises the question: Where does Supergirl go next? Particularly in regards to DC Comics guest stars, given that season 1 surprised audiences by throwing an impressive collection of DC villains, Superman supporting castmembers, and even an interdimensional cameo from The Flash at Kara Zor-El. One can only wonder who might be turning up for season 2 - especially given that the (for now) last thing we saw the heroine do was rip open the cockpit of a freshly-crashed Kryptonian spacepod identical to the ones that brought her and Superman to Earth and exclaim "Oh my God!" at whatever (or whoever) she saw inside.

With that in mind, here are 15 characters - some good, some bad, some... complicated - that we'd love to see in Supergirl: Season 2

KRYPTO

krypto the superdog supergirl

One of the main things that's earned Supergirl such positive notices (and an already loyal following) is that the series decided early on to buck the trend of grim self-seriousness that's served as the default for so much of the superhero genre (and DC superheroes in particular) and instead double-down on the kind of sunny, happy-go-lucky positive energy that also worked so well for The Flash. The series specializes in characters striving to hit so high on the likability scale that they're practically cuddly - and what's more cuddly than (Super)Man's best friend?

First appearing in the pages of the original Golden Age Superman comics (where Superman had already started wearing his costume and having adventures as a teenager in Smallville), Krypto the Superdog was a fixture of the Gold and Silver Age Superman mythos and often figured in the mostly Smallville-set early Supergirl stories. Originally conceived as Kal-El's childhood puppy (sent to Earth ahead of him to test Jor-El's escape rocket technology but arriving over a decade later), few things would fit both Supergirl's gooey-hearted earnestness and memetic social-media friendly marketing better than an adorable pooch with super-strength, heat-vision and flight powers of his own. Imagine the reaction if it's him in that mystery ship (or Streaky the Supercat, his feline counterpart).

MR. MXYZPTLK

mr mxyzptlk supergirl

It's something of a running joke that, despite their powers and pop-culture ubiquity, Superman and Supergirl don't have a particularly big stable of memorable villains compared to the likes of, say, Batman or Spider-Man. But the ones they do get tend to be doozies - think of it as a quality over quantity thing. Case in point: Mr. Mxyzptlk.

An impish magic-user from The Fifth Dimension, Mxyzptlk is unbound by the laws of physical reality and visits Earth (or, rather, the dimension that Earth occupies) to play "pranks" that often have dire consequences that he claims to be too highly evolved to recognize the gravity of... or he's just a sadist with the power to alter reality itself, it's varied over the years (no less than Alan Moore identified him as Superman's greatest foe in his hypothetical "final" Superman story "Whatever Happened To The Man of Tomorrow?"). Kryptonians being the only beings on Earth as close to beyond all physical limits as he is, the Man of Steel is among Mxyzptlk's favorite targets - but he'd be a natural fit for Supergirl: The emotional core of the series' character drama is Kara struggling to manage her complicated life and delicate personal relationships; a perfect target for a creature who lives to set off chain-reactions of annoying havoc "just because."

VALOR

valor lar-gand mon-el supergirl

Superman himself exists in the universe of Supergirl, but thus far the series has held to an unofficial rule that he doesn't appear in the show other than as an offscreen presence, a shadow or a briefly-glimpsed blur of motion. Funny, sure - but if the series did ever decide than an episode or two required the presence of a Clark Kent-esque super-figure, the DC canon has plenty of them.

Among the best fits for a "Superman, but not" suporting role among them would surely be Valor, aka "Lar-Gand," aka "M'Onel," aka "Mon-El." Believe it or not, his origins are almost as convoluted as his name: Originally an amnesiac alien with powers similar to a Kryptonian (he's allergic to lead instead of Kryptonite - that's about it) briefly assumed to be Superboy's brother and later retconned Post-Crisis as a visitor from another dimension; the important thing is that he dresses like a palette-swapped Superman and (like Supergirl) has ties with the Legion of Superheroes.

Speaking of which...

THE LEGION OF SUPERHEROES

legion of suoerheroes supergirl

Supergirl's visit to her cousin's secret arctic retreat in "Solitude" was full of easter eggs for eagle-eyed DC fans, but the one that set tongues wagging was a prominently-displayed ring bearing the unmistakable insignia of the Legion of Superheroes - a 30th Century club of teenage heroes who rebelled against their apathetic future society by embracing costumed-crimefighting lifestyles modeled on historical records of Superboy, whom they frequently encountered personally through time travel.

Given that they were established as the far-future of the DC Universe yet said to have been inspired by a character (the original Superboy) who isn't supposed to exist Post-Crisis, The Legion's history is convoluted to say the least. But a version of their original concept - essentially superhero fanboys and fangirls who've taken their obsession to the logical positive-extreme - would be rife with possibilities for a series like Supergirl that's all about the lighter side of caped-crusading. Plus, their massive and diverse membership roster (Bouncing Boy, Triplicate Girl, Shadow Lass and Matter-Eater Lad are among the more infamous) offers near-endless possibilities.

MARY MARVEL

mary marvel supergirl

If the non-superheroic parts of Supergirl's ongoing narrative are about anything, it's the importance of having a strong support-system. Kara Zor-El has mentors, friends and family helping her navigate the various pitfalls of her life - and thanks to Multiversal travel she even knows one other plucky Millennial superhero in Barry Allen's Flash. but one thing she hasn't encountered yet is an ally who "gets" all three parts of her life: Superhero, secret-civilian and young woman.

The female counterpart and twin sister of Billy Batson (a young boy who becomes the Superman-esque "Captain Marvel" when he says the magic word "Shazam!"), she's got his same basic powers and thus a similar "girl hero in the shadow of a more famous male relative" set of baggage to Kara's own. Corporation-confusing naming scheme aside, The Marvel Family are always a fun addition to a DC super-story - and unlike Kara's relative(s), Warner Bros. would likely be less skittish about letting the "TV teams" play with Captain Marvel and Captain Marvel Jr.

SELENA

faye dunaway as selena in supergirl

There are plenty of loose threads for Supergirl to pick up in its second season, but short of the fate of Dr. Danvers and the occupant of the mystery ship the next biggest has to be the presence of The Omegahedron; last seen in the hands of Maxwel Lord.

Notably, The Omegahedron is an easter egg for fans, but unlike others of its kind it doesn't originate in the comics: It's from the original 1980s Supergirl movie. In that infamously campy cult-classic, the all-purpose magical device was sought by Faye Dunaway as Selena, a witch who served as Supergirl's main nemesis in the film. Witches are always fun to have around in a genre show, and an update of Selena - a vamping, over-the-top diva who used her powers mainly to accrue wealth and seduce attractive male suitors - would be an entertaining presence in this new Supergirl's more modern but still decidedly female-forward cast.

STARGIRL & S.T.R.I.P.E.

stargirl stars and stripe supergirl

One of the more unusual superhero duos of the WWII-era Golden Age was The Star Spangled Kid and Stripesy, notable for being the only such superteam where the leader was a teenager (hence "Kid") and the loyal sidekick was an adult - the kid's mechanic and muscle, so nicknamed because of his red and white striped shirt.

In 1999, DC superstar writer Geoff Johns created a new-generation update of the concept wherein the elderly Stripe sey's (real name: Pat Dugan) stepdaughter Courtney Whitmore discovers his secret past and decides to become the new Star Spangled Kid - later renaming herself "Stargirl" after being bequeathed the magic staff of fellow DC legacy-hero Jack Knight, aka "Starman." To help her, Dugan resumes his sidekick/muscle role via a suit of powered armor called S.T.R.I.P.E. Stargirl and Supergirl have been friends and occasional allies in the comics and in the animated series Justice League Unlimited, but her stature as a young female claimant to a male hero's legacy backed up by a father figure in a support role would maker her uniquely well-suited for Supergirl's overarching themes; plus, she's already made at least one live-action appearance previously on Smallville. How well suited is Courtney Whitmore for Supergirl's whimsical take on the DC mythos? She (canonically) bases her costume on her favorite cartoon character, a DC funny-animal mainstay named Yankee Poodle.

BIG BARDA

Big Barda

Someday, someone will give Jack Kirby's "Fourth World" characters - a universe-within-a-universe of trippy cosmic characters inhabiting the DC Universe - the sprawling Star Wars-style blockbuster treatment it deserves. Until then, fans will just have to be content with it's myriad inhabitants, particularly The New Gods, making sporadic appearances throughout mainstream DC adaptations - like this one.

A towering amazonian warrior woman of Apokolips married to the significantly less mighty escape artist Scott Free, a.k.a. "Mister Miracle," Barda is the rare comic book "lady bruiser" whose as much a figure of comedy as action; a turncoat veteran of Darkseid's infamous Female Furies who lives for battle but also fixates devoutly on trying to be a "normal" Earth housewife to Scott. An offbeat, quintessentially Kirbyesque mash-up of Bewitched's Samantha Stevens and The She-Hulk, she's like nothing else in the DC superheroine pantheon - and she (and Mister Miracle himself, for that matter) would make wonderfully unique guest stars for Supergirl.

BATGIRL

Batgirl

Warner Bros (and thus DC) is protective of Batman as a live-action character - and why shouldn't they be, considering he's the only DC hero who's been consistently reliable for returning positive box-office and good reviews for the better part of two decades. That's partially why a young Bruce Wayne wasn't permitted to be a character on Smallville, and likely why, even though his existence has been obliquely referenced on Supergirl, he's shown up even less than Superman has (read: never) - and it's likely to stay that way.

But that hardly means that the same has to apply to Batgirl, a.k.a. Barbara Gordon. In the comics, Supergirl and Batgirl are as long-established as friends and allies as their male counterparts, and they've teamed up in several animated adaptations as well. Just about anything Batman-related is all but guaranteed to draw attention, and the TV series' creators would no doubt enjoy the all-but inevitably positive comparisons to the male Super/Bat crossover that by then will have long since left theaters but likely not the audience's collective memory. More importantly, there's plenty of thematic material and character drama to be mined from Kara encountering a fellow superheroine fighting the same fight without any of her special powers.

THE QUESTION

Renee Montoya The Question

A downside to the idea that Batman is likely on the "do not touch" shelf as far as Supergirl's access to the DC pantheon goes is that the contrast between The Dark Knight (adult, male, dark, violent) and Kara (young, female, sunny, a protector) would make for some snappy back and forth. Fortunately, Bruce Wayne is far from the only grumpy, punch-first-and-ask-questions-later crimebuster stalking the DC Universe.

Created by original Spider-Man artist Steve Ditko in the 1960s as a superheroic avatar for his Objectivist political philosophies, The Question (originally Vic Sage, a muckraking journalist) terrorized criminals with mastery of the martial-arts and his distinctive featureless, flesh-colored mask first at now-defunct Charlton Comics and later at DC; where he also served as the inspiration for Watchmen's Rorschach. Worth noting, Sage died from cancer in the pages of the well-regarded DC maxiseries "52" in the early 2000s; but the mantle (and hard-edged film noir attitude) of The Question were passed to Renee Montoya, a hard-living ex-Gotham City policewoman (originating in Batman: The Animated Series) and sometime love interest of Kathy Kane, aka Batwoman. Along with being a fun, fan-favorite figure from the comics, an LGBT Latina answer to Jessica Jones would bring several welcome new shades to Supergirl's character spectrum - plus, it'd be a clever "Multiverse" gag if Victoria Luz Cartagena were to reprise the role after playing the (non-Question) version of Montoya in the first season of Gotham.

POWER GIRL

The Flash Multiverse Kara Power Girl

In the DC Extended Universe, the "Multiverse" concept exists so that characters like The Flash and Supergirl can hop between each other's series without rival networks having to coordinate too much, and so Supergirl's unseen version of Superman can be a presence without having to worry about whatever Zack Snyder is up to in the movies. But in the comics it was first invented to explain away continuity hiccups, and later to explore different takes on familiar characters. For example: On "Earth 2," Supergirl grew up to give herself a new name - and a whole different attitude.

Earth 2's heroes were older than their Earth 1 counterparts by about a decade, and Earth 2's Kara Zor-El had gone through some big changes in those years: Embracing a decidedly 70s-flavored "militant" feminist philosophy and changing her name and costume to more sharply step out from her male cousin's shadow - to the extent that, when gifted with a new chest-insignia that referenced the original "House of El" crest, she took it as such an insult that she left a symbolic opening in her costume instead... which, clearly, had nothing to do with the artists looking to more prominently feature the dramatically-enlarged cup size it had at some point decided that Earth 2 Kara possessed.

But while Power Girl's infamous "cleavage window" likely wouldn't make it onto TV, having the occupant of the mystery ship turn out to be another universe's Kara would be a hell of a twist to open Season 2 with, and Melissa Benoist has honed her impossibly-upbeat Supergirl persona to such perfection already it'd be a riot to see her play a jaded, cynical hardcase version of the "same" character.

MISS MARTIAN

Miss Martian Young Justice

Supergirl pulled off the biggest twist of its first season when, despite sporting the name of DC villain Cyborg Superman, Hank Henshaw was revealed to actually be J'onn J'onzz: The Martian Manhunter. With subsequent episodes fleshing out the show's version of the comics' often confusing Martian mythos up to and including the villainous White Martians, it only makes sense for DC's second most-prominent visitor from The Red Planet to make an appearance - especially because she'd be welcome as a fellow superpowered alien woman for Kara to confide in.

Known to her friends as M'gann M'orzz ("Megan Morse"), Miss Martian is a relatively recent creation of DC comics whose history has been marked by several convoluted storylines about time-travel and body-switching, but who has developed a passionate fan following all the same - particularly among viewers of the cult-hit animated series Young Justice. A White Martian who chooses to present herself as a Green Martian through shape-shifting, she's been adopted by some fans as a metaphor for living (and coming out) as transgender; and her "magical girl" Anime-inspired costume and character design has made her a favorite of the cosplay circuit.

LORI LEMARIS

Loris Lemaris Superman Mermaid

Lori Lemaris, in one of the most unusually melodramatic Golden Age Superman stories ever (and that's saying something), "The Girl in Superman's Past." A flashback tale, it reveals Lori as Clark Kent's college girlfriend, his key romantic relationship between his teenage romance with Lana Lang and Lois Lane as an adult - a relationship that was stymied in part by Lori being confined to a wheelchair, her legs always covered by a blanket (yes, the man who could fly loved a woman who couldn't walk) and by her insistence on never staying out too late for mysterious reasons not revealed until the end:

She's actually a mermaid - and the wheelchair and blanket are a disguise to conceal her tail.

Part of Supergirl's endearing charm to this point has been its staunch willingness to wear the "girl" part of its title unashamedly - not necessarily wallowing in stereotypically feminine genre tropes, but also not being afraid of them either, i.e. letting themes like sisterhood, gender-labeling dynamics ("What do you think is so bad about ‘girl’?”) and romance drive as much if not more of the storyline than alien invasions and super-powered battles. Plenty of strange creatures have already made themselves known as part of the DCEU TV series, sure... but if there's one in the bunch that could get away with "Hey, look! There's a mermaid now!" it's Supergirl. Besides, few characters would likely prove more fascinating to Kara than a woman who'd dated Superman back when he was her age.

COMET

Supergirl with Streaky the Cat and Comet the Horse

Supergirl has a horse. That's something a lot of female superheroes tend to get, perhaps because for a decent stretch of time largely male comic book writers' knowledge of what might appeal to a female readership begins and ends with "stuff my daughter likes." Regardless, Supergirl has a horse named Comet who can fly and manifests other Kryptonian-esque powers despite not technically being from Krypton - and that's not even the strangest thing about him. For one thing: He has human-level intelligence and an interior monologue. For another thing: He's secretly in love with Supergirl. And for another thing: He's not actually a horse.

So goes the story: Comet is actually a centaur (half-man/half-horse, if you've misplaced your Monster Manual) from Ancient Greece named Biron, who fell in love with a human girl and sought out a potion to make himself fully-human from a witch. Unfortunately, the witch's nemesis interfered with the potion, transforming Biron fully into a horse instead. Unable to undo the spell, the witch sought to make up for the error by granting Biron super powers such as flight and immortality - thus explaining how he lives long enough to be in then present-day Smallville to be adopted and rechristened "Comet the Superhorse" by Supergirl. It's later revealed that, because of machinations by the same interfering sorcerer from earlier, Comet's life-force is effected by a comet (outer space kind) that period passes by Earth, temporarily transforming him into a human who can woo Supergirl (who has no idea about any of this - just so we're clear) in the guise of macho rodeo star "Bronco" Bill Starr.

If you can't get an hour of watchable television out of that, you aren't trying very hard.

SUPERMAN

15 Characters We Want To See In Supergirl Season 2

Let's not kid ourselves: The elephant in the room of Supergirl guest-stars is the question of whether or not Superman will ever actually show himself on the series.

It'd certainly be the biggest stretch for the Multiverse so far, with Superman being far and away the biggest character to be seen in two different incarnations, let alone across two different mediums between film and television. And it's a "dynamite option" guest spot that can really only work once, since making him a regularly featured player would begin to dilute the purpose of the series. Sure, "Superman swoops in to fight by Kara's side against the biggest odds she's ever faced" is an easy enough logline to write into an episode summary, but once you've done it where do you go? Since Superman can't keep showing up all the time after that, you're essentially writing "it's all downhill from here" into the DNA of every subsequent challenge: Well, no sign of Superman, so this can't be that big of a deal! Plus, there's the question of actors: Do you spend the money to bring Henry Cavill in for an expensive TV cameo, or do get another you bet on audiences getting/accepting that Kal-El of Supergirl's Earth looks different from Kal-El of Batman V Superman's Earth "just because."

And yet... plenty of fans would likely welcome his presence, if only for a moment. For all the talk of film-critic snobbery, a backlash in general comics fandom regarding Man of Steel and Dawn of Justice is very real - and many fans have taken (fairly or not) to holding up Supergirl, Flash, Arrow and Legends of Tomorrow as a hallmark of The DC Universe "done right." And given how much of the criticism of the DC movies has centered on Superman (supposedly) being unrecognizable as himself, a Last Son of Krypton executed in that particular style and tone would almost certainly be embraced by a what seems to be a sizable audience - though whether Supergirl is really the ideal place for that to happen is likely to remain another story entirely.