Anti-alien racism flares up with a new demagogue called "Agent Liberty."
- Doppelmerger: In the Season 3 finale, Kara comes into contact with Black Kryptonite, which creates a clone of her. The clone is found in Kaznia and raised as a a loyal communist soldier named Red Daughter. After some time as an antagonist in Season 4, Red Daughter sacrifices her life to save Supergirl and remerges with her.
- Fantastic Slur: The Children of Liberty take to calling the aliens "roaches," since they infest the planet and are very difficult to kill.
- Tyrant Takes the Helm: After a few too many times of the DEO handling things in a way President Baker doesn't like, he assigns Colonel Hayley to oversee it and Alex as Director. The trope is Zig-Zagged, as Hayley initially seems like she'll be this trope, then we see her in action and she seems a Reasonable Authority Figure... who, as soon as the crisis has past, starts dropping xenophobic slurs and insisting Alex salute her. Alex even compares her to former Trope Namer Dolores Umbridge. Finally, Hayley turns out to be actually fairly reasonable, just strict, by-the-book, and far less accommodating of unusual approaches to problem-solving, even if they work, combined with a fairly strong My Country, Right or Wrong, I Did What I Had to Do, and Just Following Orders mentality.
