The best (and worst) Supergirl episodes from all 6 seasons of The CW show
Best and worst Supergirl season 3 episodes
Season three might just be the best season of Supergirl overall, with engaging character dynamics and a relatively cohesive season-long arc. Kara no longer feels like the female Superman, and while her depression over losing Mon-El can be difficult to watch, it is undoubtedly her journey. Kara's morality comes into question, and the decisions of Lena, Alex, and Sam all feel rational and in tune with their personalities.
Best: Season 3 Episode 9, "Reign"
With eight episodes of build-up coming to fruition, "Reign" was destined to either be amazing or a terrible disappointment. Thankfully, it was a success. From action to character arcs, this episode was firing on all cylinders. It feels like a culmination of all that has happened up to that point, as well as driving the plot forward and making fans desperate for the next episode.
Reign is a terrifying villain because she is both a serious threat to Supergirl and a parasite of sorts to Sam. Rather than being a person who can be reasoned with, she is a force of nature. This sets up some great conflicts for the season because none of the group's usual strategies is going to be able to stop her.
The other side of the episode involves Kara's pain at seeing Mon-El and Imra's relationship. While many fans hated this arc (either because they never liked Kara and Mon-El together or because they hated that they were torn apart), it's really well done here. Media often paints the other woman as a monster, but Supergirl takes the unique stance that sometimes relationships just don't work out, and an ex's future partners aren't wrong for having their own happiness.
Kara is finally facing threats in her personal life and as Supergirl that she isn't able to overcome with force or hope. That combination makes for one of the best episodes in all of Supergirl.
Worst: Season 3 Episode 21, "Not Kansas"
"Not Kansas" was the worst-rated episode of season 3 by far, with half a point between it and the next-lowest-rated episode on IMDb. Much of this ranking was based on viewers who were upset with the way gun control was handled in the episode. However, the bigger problem with the episode was that the characters were making choices that didn't fit their arcs.
After years of living on Earth and two and a half years as its protector, Kara decided that she needed to move to Argo City, the home of her mother and other Kryptonian refugees. This is similar to the controversial choice in the MCU for Steve Rogers to abandon his life and friends in the present for a secret romance with Peggy Carter. While some like the idea, it feels contrary to what we know of the character.
Back on Earth, J'onn and James deal with the aftermath of military-grade weaponry becoming available to the public. While this was clearly meant as a discussion of gun control in the real world, it didn't go over well in the show. Frankly, it doesn't make sense for a military organization fighting aliens and superhumans to completely eliminate guns and other weapons that would be lethal to humans.
Across both plots, the characters act contrary to their established personalities. While Kara was struggling with her place after losing Mon-El, it doesn't feel realistic that she would choose to leave altogether, especially after learning about Krypton's many failings. Similarly, while J'onn has been actively moving toward the pacifism his father preached, his rejection of weapons at this moment felt forced.
Fans love the characters as they are, and while it's absolutely worthwhile to show them growing and changing, that should never happen without reasonable time and cause.