Supergirl has been a huge part of comic book culture since 1959, so when Ali Adler, Greg Berlanti and Andrew Kreisberg set about reviving her for the small screen in 2015, it's safe to say they had a sizable amount of responsibility upon their shoulders. Not only did she have decades-worth of storyline and history to contend with, there was also the fact that she'd be the first female lead in the Arrowverse; something that television creatives would never take lightly considering the emphasis on increasing diversity in the mainstream these days.

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First, they were tasked with deciding which version of Supergirl to concentrate on, understandably opting for Kara Zor-El, the most recognizable woman to adopt the moniker and who just so happens to be Superman's cousin. It seemed like an obvious choice -- particularly as she'd already been the subject of a television show in the '80s -- but narrowing down which villains to include, supporting characters to introduce and romantic relationships to write il would be trickier. As a result, significant changes were made in the name of artistic license. Some alterations definitely improved on the source material while others really didn't land. In the following list, we take a look at some of those less successful differences.

15 MARTIAN MANHUNTER

Everybody loves David Harewood's version of J'onn J'onzz, aka Martian Manhunter. Not only is he an awesome father figure to the Danvers sisters, he also has a decent backstory and first-class superpowers too. So, what's the problem with how The CW portrays him? Well, it's that it doesn't seem to let him use his powers...

Back in season one, J'0nn's alien identity was hidden from several characters for the majority of the series, which explained why he couldn't just transform into his Martian self and kick butt whenever he fancied. But considering his heritage is less of a secret now, why doesn't he ever help Supergirl when she's finding it difficult to beat a baddie? It makes no sense! Basically, we want more Martian Dad. Similarly, CBR would like to add that since the show moved to The CW, Kara hasn't shared nearly enough scenes with her sister Alex either...

14 MON-EL’S BACKSTORY

After Supergirl moved to The CW, Mon-El (Chris Wood) was introduced into the show. Arriving to Earth via pod, the character hails from Daxam; a planet that feuded with Krypton. Later, it was revealed that Mon-El was actually a prince on his former planet and selfishly abandoned his people when Daxam was dying. Despite his past, Mon-El was eventually inspired by Kara's heroic ways, vowed to become a good person and help her fight crime.

His backstory -- and character -- within the comics was slightly different. Lar Gand, as he was known then, was originally an explorer who landed on Krypton and was instructed to travel to Earth by Supergirl's uncle Jor-El. Upon landing, he suffered amnesia and meeting Superboy, assumed they were long-lost brothers and called himself Mon-El. 'Mon' as he arrived on Earth on a Monday and 'El' for his new acquaintance's own Kryptonian family name.

13 MAGGIE SAWYER’S DEPARTURE

Many Supergirl fans are disappointed that Floriana Lima's Maggie Sawyer has exited the show so early on in its third season; particularly those who were grateful for the LGBT representation she provided within the diversity-challenged mainstream media. But losing Maggie isn't just a shame because it means said representation will now be thinner, it's also because it's obvious The CW didn't make the most of her inclusion in the first place.

Unlike her on-screen other-half, Alex Danvers, Maggie is a character that stems from DC Comics. Across her life in literature, she has been a Gotham City Police officer; an inspector for the Metropolis Special Crimes Unit and is a pretty big deal. Canonically lesbian, she had a serious relationship with Batwoman too; something that would have been awesome to explore on the show. Instead, it seems she merely served as a plot device to fuel Alex's coming out arc.

12 TONING DOWN SUPERGIRL’S ABILITIES

In Arrow, it's not unusual to see Oliver Queen go up against another bow-and-arrow wielding villain. In the past, he's fought the likes of Malcolm Merlyn, Nyssa al Ghul and Prometheus. The same goes for Barry Allen, aka The Flash, who has faced off against speedsters such as Reverse-Flash, Trajectory, Zoom and Savitar.

When the Arrowverse's titular heroes find themselves fighting baddies with similar skills to themselves, it often provides audiences with thrilling battle scenes as it's not obvious how one might best the other. The same can't be said for Supergirl. As Kara is Kryptonian, she's rarely exchanges blows with antagonists as powerful as her, which is why several of the show's fight scenes are rather unmemorable and more annoyingly, unrealistic. In truth, Supergirl could easily beat 90% of the villains she faces with her freeze breath or heat vision alone, so it's frustrating to watch her frequently struggle.

11 ADAM GRANT'S DEATH

In Supergirl's first season, Cat Grant's eldest son Adam Foster (Blake Jenner) makes an appearance. His involvement largely revolves around his estrangement from his mother and briefly dating Kara. Adam is actually 'Adam Grant' in the comics; Cat's youngest son and has a much darker storyline. In Superman vol 2 #84 "Toys", Adam is kidnapped by Winslow Schott/Toyman. In the issue, Adam and the other victims manage to release themselves from Toyman's lair but tragically, the villain learns of their escape and murders Adam as they are fleeing. Toyman then dumps his body in Suicide Slum.

Technically, Adam Foster's storyline played out when the show still aired on CBS rather than The CW, so it seems a little unfair to highlight it as an alteration made by the latter. Also, Adam Grant's narrative would be far too tragic for a superhero show that's typically suitable for young audiences.

10 HER ORIGIN STORY

Throughout Supergirl's existence, there have been several versions of her. Supergirl centers on Kara Zor-El, Superman's cousin. In the show, it's established that Kara lived on Krypton until she was 13-years-old but was forced to flee the planet when it became unstable. When she eventually landed on Earth, she was immediately taken in by Jeremiah and Eliza Danvers, a pair of scientists who have a daughter named Alex.

Kara's beginnings are slightly different in the comics. She wasn't technically born on Krypton but rather Argo City, an area of the planet that had survived the explosion and drifted into space. When Argo City is attacked one day, Kara's father sends her to Earth, in the hope that Kal-El will raise her but she ends up in an orphanage and is adopted by Fred and Edna Danvers. The New 52 version of Supergirl's origin is closer to that of the show.

9 LOSING CAT GRANT

To some, it might not seem like the switch from CBS to The CW really affected Supergirl; after all, it still has the majority of the same characters, actors and story lines that it had before. However, there was one significant -- and arguably, damaging -- change that came about because of its move across networks and that was losing Calista Flockhart as media mogul and Kara Danvers' mentor, Cat Grant.

The shift meant that Supergirl's filming location changed from Los Angeles to Vancouver in Canada, and the California-based star could not be as involved going forward as a result. Despite appearing in every single episode of the show's first season, she's only featured in three episodes throughout the second and third seasons so far, and it's safe to say that fans sorely miss her motivational speeches and matter-of-fact life lessons.

8 JAMES OLSEN

Supergirl's decision to make James Olsen a lot cooler than he is in the comics was great. Unfortunately, that is the only good decision the show ever made when it comes to Mehcad Brooks' version. During the first season, James joined CatCo as art director and quickly became good friends with colleagues Winn and Kara. It was established that he'd moved to National City from Metropolis to watch over Kara as a favor to his good friend -- and her cousin -- Clark Kent. Before long, James and Kara developed romantic feelings for one another.

But shortly after the pair got together -- and it appeared as if they would be an item going into season two, Kara inexplicably told James that they should remain as just friends. Since then, James has been criminally sidelined and it sucks. Even his transition into Guardian was clumsy and went nowhere!

7 KARA AND KAL’S EARLY RELATIONSHIP

While Supergirl's opening may spell out that Kara Zor-El and her cousin Superman knew each other back on Krypton, the pair weren't as familiar in the comics. Initially, baby Kal-El was sent to Earth just before Krypton exploded, while Kara was born years later. Kara was then sent to the blue planet by her own father, in the hopes that she'd be watched over by Kal and given a uniform similar to Kal’s so that he would recognize her.

In the series, however, it was the other way round. Kara was sent to Earth as their planet was dying to look after baby Kal. Kara's pod was knocked off course though and she ended up in the Phantom Zone, where time stands still. She awakened 24 years later, continued her journey and when she landed on Earth, Kal had already grown up and become Superman.

6 DEATH OF KARA ZOR-EL’S BIOLOGICAL PARENTS

Because the series combines several versions of Supergirl, it stands to reason that a lot of her backstory, and the backstories of those who surround her, have been altered. In the show, Kara's parents, Zor-El and Alura, died when their planet Krypton exploded. Despite managing to send Kara to Earth in an escape pod, the pair didn't have time to flee themselves; a notion the frequently fills Kara with both guilt and gratitude.

In the comics however, Kara's parents individually survive, become an item and have Kara when they meet on Argo City, an area of land that separated for Krypton in the explosion. They also survive when a deranged Argo citizen veers the city into a swarm of meteors, which is when they actually send Kara to Earth. Later though, Zor-El is killed by Reactron, one of Supergirl's adversaries, and Alura dies when Lex Luthor destroys New Krypton.

5 SUPERGIRL AND MON-EL

Supergirl has been romantically linked to characters such as Dick Malverne, Jerro and Brainiac 5 in the comics but The CW's show has seen her cozy up to three different figures; Cat Grant's son Adam Foster, James Olsen and most significantly, Mon-El. While there's no denying the chemistry between real-life couple Melissa Benoist and Chris Wood, Mon-El was a questionable addition. Its second season centered heavily on the Daxamite; exploring his heritage, his relationship with Kara and having his mother Rhea (Teri Hatcher) as the series' big bad.

His overwhelming presence forced Kara into the role of 'girlfriend' rather than 'protagonist' and it didn't go down well with fans. While Kara grieving over Mon-El's departure from Earth was the focus of the third season's opening episode, he hasn't been mentioned much since and you can already see her becoming her own character again. It's undeniably a good thing.

4 LENA LUTHOR

Lena Luthor's relationship with Kara Danvers differs greatly within the comics. In the show, Lena met Kara as an adult but in the original material, she knew a version of the character back when she was living in an orphanage. Aside from the alteration, the show's pairing have proved a popular discussion point among fans. Many ship them as a romantic pairing and it's easy to see how they arrived there.

Melissa Benoist and Katie McGrath have an obvious rapport with one another and if truth be told, some of their scenes could be misconstrued as flirty -- come on writers, you even included a moment that saw Supergirl carrying Lena like Superman carries Lois -- but alas, the creatives claim they're merely best buds. We do wish the show wouldn't make it so difficult to see it that way though... Queerbaiting -- intentional or not -- is never fun!

3 ROMANCES THAT GO NOWHERE

A fictional romance doesn't need to necessarily "go anywhere" or end up panning out for it to be worthy of inclusion and make an impact, but Supergirl has featured an unforgivable amount of pointless love interests for a show that's been running for less than three seasons. Therefore, it has to be mentioned within this list.

First, it transpired that Winn Schott had a crush on his long-time friend Kara Danvers; something that was brushed under the carpet ridiculously quickly. Elsewhere, there was a brief flirtation between Kara and Cat Grant's son Adam Foster, as well as semi-awkward sparks between Alex Danvers and Maxwell Lord. The two most embarrassingly meaningless relationships on the show, however, were undoubtedly between James Olsen and Kara and Winn and Lyra; an alien that the DEO agent met in a bar.  Both were built up so much, only to be shot down almost immediately.

2 SUPERGIRL IS TOO MUCH LIKE SUPERMAN

In the run-up to Supergirl's debut in 2015, executive producer Sarah Schechter assured expectant fans that Superman would not be appearing in the show "because it’s not about him." Her comments made perfect sense, but even before Clark Kent showed up in season two, it was easy to see how Superman loomed large over the series without physically being a part of it; with constant mentions, the inclusion of several Lois and Clark/Smallville actors, and through Supergirl herself.

In the comics, Kara works as a reporter when she's not fighting crime -- just as Clark does -- which is something that the Supergirl writers were unlikely to change. However, the show could have been the perfect opportunity to finally differentiate between the two Kryptonians. Instead, fans have been presented with a cookie-cutter hero that closely resembles Superman's optimistic alien and who just so happens to wear spectacles in their down-time.

1 SUPERGIRL ISN’T ALWAYS THE SHOW’S FOCAL POINT

Despite us pointing out the differences between the comics and the television show, we understand that alterations are made to make the latter easier for non-comic book readers to follow. Seeing as she was first introduced in the '50s, Supergirl has decades worth of material that the show's writers just do not have the time to go into, so they have to bend story lines and backstories accordingly to make episodes flow.

That being said, Supergirl -- much more so than other series within the Arrowverse -- tends to forget that viewers actually want the eponymous superhero to be the show's focal point. With its week-by-week villains and growing number of supporting characters, Supergirl struggles to weave story lines together, often resulting in messy, convoluted. Kara often gets sidelined, only showing up to save the day when the Department of Extranormal Operations call.

Do you agree or disagree with us? Make sure to sound off in the comments!