For the eponymous group, see The Legion.
"Legion of Super-Heroes" is the tenth episode of the third season of Supergirl, and the fifty-second episode overall. It aired on January 15, 2018.


Struggling to heal from her injuries inflicted by Reign, Supergirl remains in a dreamlike state, unable to be reached. Mon-El recruits one of the Legion members, Brainiac 5, to try to bring her back. Meanwhile, Reign continues her rampage on the city so the DEO teams up with the Legion of Superheroes to try to stop her.[1]


Mystery Coluan

Brainiac 5 in a pose reminiscent of Mystery Man from "Lost Highway".

  • The binary code 0011101000101001 that Brainiac 5 wrote on Alex's cast translates to ":)", a common ASCII depiction of a smiley face.
  • The setting being partially inside Kara's subconscious, the clothes and poses of Brainiac 5, along with certain quotes of his while mentally speaking with Kara, are all greatly reminiscent of David Lynch's "Lost Highway", particularly the character of Mystery Man.
  • Kara's cat Streaky introduced in the episode is a reference to Kara's superpowered cat from DC comics.
    • Kara reveals she found Streaky on her street right after she came to Earth. He was a stray, giving her an emotional kinship to him. She used to go out every night and feed him, but didn't wanna touch him cause she was scared or hurting him. So she practiced being gentle, and one day she finally pet him. He purred, making her feel like everything was going to be ok.
  • Mon-El mentions the name "Ayla" as one of his friends from the 31st century. This is a reference to the DC superhero Lightning Lass, another member of the Legion of Superheroes.
  • The Sundown Protocol.- A highly-classified contingency plan to take down Superman if ever he turned evil. Red sun grenades, sound bombs, Kryptonite darts, everything needed to take down a rogue Kryptonian on the loose.
  • Mon-El reveals in 1,000 years a farming planet called Winath goes dark. Their friend Ayla goes to check it out, and found decimated. Completely dried out. The creatures that did it are called The Blight, and they consume everything in their path. Brainiac 5 found a way to stop them, but they were on them before they could use it, and hid the information in their DNA.
    • He also reveals Supergirl lives though her ordeal, and Reign will leaves eventually.
  • During the fight with Reign, Alex broke her tibia (lower leg).




  1. Supergirl - Episode 3.10 - Legion of Super-Heroes - Promo + Press Release - SpoilerTV