The Grand Finale.
The Superfriends have their Final Battle with Lex and Nyxly, Alex and Kelly get married, and Kara makes an important decision about her life.
Tropes:
- Actor Allusion: Eliza wonders if she could have been a Kryptonian in a previous life. Alex responds, "Only in the movies," referring to Eliza's actress Helen Slater having played Kara in the 1984 Supergirl film.
- And the Adventure Continues: The series ends on that note, with the Superfriends still being active and celebrating the next chapters in their respective lives.
- Artistic License – Physics: It's mentioned that Lex and Nyxly using the Allstone is draining the emotions from people permanently. Except, energy, even emotion energy, doesn't work that way. Energy cannot be created or destroyed, only change forms. Given what the power source is, the energy expelled by the Allstone should have gone back into wherever it was drained from after being used up.
- Babies Ever After: Winn reveals that M'gann and J'onn will have a son in the future.
- Back for the Finale: James, Winn, Mon-El, Eliza, and Cat Grant all make appearances.
- Big Damn Heroes: Several.
- Mon-El shows up helping Kara, blocking Overgirl's heat vision.
- Winn pilots his ship, supporting J'onn against the Kryptonite dragon.
- James helps his little sister against Metallo.
- Andrea supports Lena against the giant dream monster.
- Eliza shoots down the owls Nyxly summons against Nia.
- Book Ends:
- The season opener ended with Lex opening up a portal to the Phantom Zone in order to trap Kara. In the final episode of the season, Lex opens a portal again but this time it ends up backfiring and the Phantoms drag him and Nyxly to the Phantom Zone.
- The series began with Kara revealing herself to the world as Supergirl. The series ends with Kara doing this again, this time revealing her secret identity to the world.
- Bouquet Toss: It gets caught by Nia with her powers. Brainy then remarks that there is a 100% chance that the two of them will marry.
- Brought Down to Badass: Despite all of humankind snapping out of their despair and greatly depowering Lex and Nyxly, the two are still able to make the heroes work for their victory.
- Brutal Honesty: Cat Grant once again gives Kara some well-meaning, but very harsh-sounding advice.
- Character Death: Lillian succumbs to the wounds she got at the end of last episode and dies.
- Clark Kenting: Brought up in conversation between Kara and Cat:Cat: So you're Supergirl. La-dee-da.
Kara: You...you knew?
Cat: Please, those spectacles disguised you about as much as a pair of Groucho Marx glasses, and you should have added the bushy eyebrows and the mustache. - Continuity Nod:
- James gives Esme a camera, noting that his father gave him one. James' camera and its subsequent breaking were important parts of his character in the first two seasons.
- During the Final Battle, Lex summons copies of Overgirl, Red Tornado, Metallo, and Parasite, while Nyxly summons her Kryptonite dragon, the Dream Realm monster, and Nia's nightmare owls.
- At the wedding, the original Superfriends (Kara, James and Winn) reflect on the early days when they all worked at CatCo.
- Lena recites the family motto of House El, 'El mayarah'.
- Winn muses, "Easy-peasy-fresh-'n-squeezy" while preparing to fire his ship's weapons, which he also said verbatim to Kara in Season One when she asked if he could hack into hospital records.
- Later, he calls J'onn "Papa Bear," just like he used to in Season 3.
- Death Equals Redemption: Despite all the terrible things she did, Lena and Lillian seem to part on somewhat good terms when Lillian encourages Lena to embrace her magic and become what she was meant to be.
- Dragged Off to Hell: Nyxly and Lex, courtesy of the Phantoms.
- Due to the Dead: William's funeral is held after Lex and Nyxly are defeated.
- Friendship Moment: Lena and Kara share one, reaffirming the deep bond they share.
- The Gadfly: Winn tells J'onn that he and M'gann are going to have a son, then walks off cheerfully, leaving the Martian gaping.
- The Ghost: Winn gives the Superfriends Mister Mxyzptlk's regards, but the latter doesn't appear himself.
- The Glasses Gotta Go: In a symbolic gesture, Kara leaves behind her glasses at the wedding, not wanting to hide her true self anymore. Soon afterwards, she reveals her true identity to the world.
- Grand Finale: The third Arrowverse series to come to a close, Supergirl wraps up with six seasons and 126 episodes.
- Heel–Face Turn: Mitch, having enough of toxic relationships, joins Kara and the rest of the citizens in their stand against Nyxly and Lex.
- Hoist by His Own Petard: Lex summons an army of Phantoms to attack the heroes, only for them to turn on him and Nyxly instead.
- Honorary Aunt: Lena becomes Esme's godmother.
- I Choose to Stay: Despite being obligated to return to the future to merge with the Big Brain, Brainy decides to follow his heart and remain with Nia in the present.
- Internal Reveal: Kara finally finds out that Cat Grant knew her secret identity. That was confirmed for the viewers at the end of Season 2 with Cat's "Go get 'em, Supergirl."
- Karma Houdini Warranty: After consistently weaseling himself out of trouble over the past three seasons, even to the point of coming back from the dead, Lex finally gets his comeuppance when the Phantoms he summons drag him into the Phantom Zone. And considering all the terrible things he's done, and the death of Lillian, the only person who still loved him, it's unlikely that anyone will be trying to save him.
- Laser-Guided Karma:
- Lex opened the season by sending Kara to the Phantom Zone after his evil plan was stopped. Here his final fate is to be dragged off into the Phantom Zone to spend the rest of his days in the same interdimensional prison he subjected her to.
- Likewise Nyxly, who clawed her way out of the Phantom Zone just to get revenge, outright refused to change her ways, and has been menacing the Superfriends all season, ends up right back in her prison to rot.
- Mirror Match: Lex resurrects Overgirl to fight Kara.
- Mythology Gag:
- The series ends with Supergirl revealing her identity to the world. Clark did the same thing during Superman (Brian Michael Bendis).
- During the battle, Brainy lets out the classic rallying cry "Long Live the Legion!"
- Redeeming Replacement: The D.E.O. is being reconstituted and J'onn plans on making it better.
- Retcon: It was shown just a few episodes prior that the Totem Energy cannot be destroyed or used up, merely changing containers. Yet, in this episode, somehow Lex and Nyxly are permanently draining the emotions of humanity to power their laser beams.
- The Reveal: Lillian reveals she always knew about Lena's magical potential and actively tried to keep her away from it.
- Rousing Speech: Via Brainy's telepathic crown and Lena's magic Supergirl speaks to the entirety of humankind, helping them snap out of their despair. Mon-El remarks that her speech made it into the history books.
- Self-Disposing Villain: Lex summons a legion of Phantoms to attack the heroes and lay waste to Earth. Unfortunately for him, Phantoms feed on fear, and the two most fearful beings present are those who have been masking it behind hubris: himself and Nyxly. The Phantoms proceed to seize them both and drag them off to the Phantom Zone.
- She's Back: Cat Grant buys back CatCo from Andrea, planning on returning to National City and making Kara her editor-in-chief.
- Ship Sinking: Mon-El tells Kara that he will no longer be able to return to the past to see her, officially ending any chance of them getting back together.
- So Proud of You: Eliza towards Alex during the wedding.
- Take a Third Option: Kara has been struggling all season with her double life as a reporter and as Supergirl and felt that she had to choose her superhero persona over a normal life. At the end of the episode Cat and Lena encourage Kara to have both by taking over as editor-in-chief of CatCo and publicly revealing her true identity to the world so she doesn't have to hide who she is anymore. Kara accepts and the series ends with her revealing herself to the world.
- Time Skip: There are three weeks between William's funeral and the wedding.
- Took a Level in Badass: Lena is able to use her magic to stand up against Nyxly's giant dream monster.
- Villain Team-Up: Despite fighting each other just moments ago, Lex and Nyxly immediately join forces again once the Superfriends show up.
- Wedding Finale: Alex and Kelly get married.
- What Happened to the Mouse?: The phalanx of heroes at the final battle includes Mitch, who is off to the side wielding a serious-looking futuristic weapon. It isn't clear why the heroes would allow this, as he could be pretending to have changed sides on Lex's orders. Mitch disappears once the villains are defeated and his ultimate fate isn't mentioned or shown.
- You Are Better Than You Think You Are: Alex encourages Kara that she will be able to master the challenge of being editor-in-chief and Supergirl. Lena later does the same.
"You know her as Kara Danvers, CatCo's ace reporter and new editor-in-chief. But tonight, it is my great honor to introduce to you... Supergirl."
