The final season of Supergirl has finally launched after being delayed, like so many other shows, by the coronavirus pandemic. After nearly six seasons of the show, the adventures of Kara Zor-El (Melissa Benoist) boasts some fantastic storylines, some of which are taken directly from the comics and others are original creations by the showrunners.
While many of these storylines were well-received, not all of the story arcs landed, especially those related to the main character. As the titular character, Kara Danvers receives the most focus, which can be both a good thing and a bad thing. It all comes down to the story being told.
Best: Red Kryptonite (Season 1)
Some of the best superhero stories around involve the heroes falling down a dark path, and Supergirl is no exception. The first time Kara gave in to her darker urges occurred all the way back in season 1, after she was exposed to Red Kryptonite.
Kara becomes someone who is cruel, selfish, jealous, and generally the opposite of herself in every way. "Falling" would've been a fun one-off episode with just this, but it turns into a larger arc for Kara when she gets publicly denounced by Cat Grant, loses the city's trust, and get J'onn exposed as the Martian Manhunter.
Worst: Maxwell Lord (Season 1)
While his appearance as the lead villain in Wonder Woman 1984 may have brought him to the attention of a wider audience, comics fans know Maxwell Lord as a powerful villain, who was once an ally of the Justice League and ended up nearly destroying them.
No one who watched Supergirl season 1 would get that, as Maxwell Lord (Peter Facinelli) is a slimy businessman who tries to outdo or destroy Kara at every turn but never comes off as too much of a threat. To make his story arc with Supergirl matter even less, he disappears at the end of the season and hasn't been seen since.
Best: Being Human (Season 1)
It may be one of Supergirl's shortest personal story arcs, the season 1 episode "Human For A Day" highlights an important moment of character development and reminds the audience of the all-important lesson that characters like Kara aren't considered heroes because of their special powers, it's because of the way they act.
After Supergirl pushes herself too far she becomes completely depowered. As an earthquake rips through Central City and Supergirl isn't there to save it, she not only learns that there are some things she can't do, but in choosing to go up against an armed robber with no powers, she can still inspire people too.
Worst: Mr. Mxyzptlk (Seasons 2 & 5)
The powerful and somewhat underrated Superman villain Mr. Mxyzptlk is a god-like imp from the fifth dimension who is similar to Q from Star Trek: The Next Generation. Considering how all-powerful Mxyzptlk is, it's perhaps not surprising that he's only appeared on Supergirl a couple of times, but in both episodes, his tremendous potential has been wasted.
In season 2's "Mr. & Mrs. Mxyzptlk" he tries to get Kara to marry him, which was insultingly silly. Season 5's "It's a Super Life" is better as it allowed Kara to deal with the repercussions of her lies to Lena Luthor, but Kara's own story arc with Mxyzptlk was cut off just as it was getting interesting.
Best: Reign And Samantha Arias (Season 3)
The season-wide story arc of Supergirl's epic third season deals with the arrival of the Kryptonian Worldkillers, in particular Reign. Thanks to an infusion of dark magic, Reign is portrayed as even more powerful than Supergirl and beats her close to death in several fights.
She is possibly the greatest challenge Kara has ever fought, but what makes the story arc even more satisfying is that Reign is an alternate personality of Kara's friend Samantha Arias (Odette Annable). Throughout the season Kara is continually pushed between taking down Reign and saving Sam, before finally managing to stop the Worldkillers by inspiring Sam rather than through violence.
Worst: James Olsen Relationship (Season 2)
Throughout the whole of season 1, the big love interest for Kara was James Olsen (Mehcad Brooks), the tough, handsome photojournalist who was close friends with Kara's cousin Superman. While Kara spurned her friend Winn Schott's (Jeremy Jordan) advances, and James himself was mostly in a relationship with Lois Lane's sister Lucy the whole season, eventually Kara and James did get together.
This lasted for basically one kiss, after which they decided they weren't right for each other and returned to being friends. So the entire love plot of season 1 was immediately dropped.
Best: Fighting Prejudice (Season 4)
Season 4 is arguably the strongest season of Supergirl. It brought in numerous mysteries, Lex Luthor (Jon Cryer), and the Red Daughter (the Supergirl version of the classic Superman story Red Son). Most importantly, it also brought in Ben Lockwood/Agent Liberty (Sam Witwer) and the Children of Liberty to shine a light on real-world prejudice.
The Children of Liberty are a hate group dedicated to eliminating aliens on Earth. While Supergirl can stop their acts of terror, the fact that she's essentially fighting against prejudice means it's a far tougher battle than even Kara may be prepared for.
Worst: The Paragon Of Hope (Season 5)
For years the whole of the Arrowverse was building to one storyline: the epic "Crisis on Infinite Earths" crossover event, which finally occurred in 2019. The key to victory against the Anti-Monitor is the seven Paragons, the purest heroes who embody the finest aspects of humanity.
Supergirl turns out to be the Paragon of Hope, something that suits her well. However, beyond the events of "Crisis on Infinite Earths," her identity as a Paragon has not been referenced and has played no other part in Supergirl.
Best: Lying To Lena Luthor (Season 2-6)
Lex Luthor's adopted sister Lena (Katie McGrath) is one of the best characters Supergirl has ever produced. Lena's desperate desire to turn the Luthor name into a force for good has always been a struggle, as she desperately fought against the rest of her family, the world's perception of her, and her own fears of becoming a bad person like Lex did.
Her friendship with Kara gave them both strength, so it was deeply upsetting for fans when Lex, in one last bitter act of vengeance at the end of season 4, revealed that Kara was Supergirl and had been lying to Lena this whole time. The fallout from this revelation drove the two friends apart and has been pushing the show to greater heights ever since.
Worst: Superman
Possibly the coolest moment in all of Supergirl was when Kara's cousin Superman (Tyler Hoechlin) properly appeared at the start of season 2 in an excellent two-part story. However, while Clark Kent's subsequent appearances are fun, his story arc with Kara is basically non-existent.
Despite them being family, Kara rarely turns to her cousin for help - either emotionally or with threats. Superman was basically written out of the Arrowverse for several years, only occasionally popping up during crossovers, and Kara hasn't even been referenced in Superman's own Arrowverse show so far. In the comics, Superman and Supergirl occasionally have a tumultuous relationship, so failing to explore them on the show leaves many disappointed.