Tonight's Supergirl didn't see the whole Legion of Super-Heroes suit up and face off with any villains in National City, but it did contain a reference to one of the team's most challenging villains.
Spoilers for tonight's episode of Supergirl, "For Good," ahead.
In the episode, Lillian Luthor (Brenda Strong) came back on a mission to get Lena (Katie McGrath) to turn evil as well as kill Morgan Edge (Adrian Pasdar). While Lena had every reason to simply let her mother kill Morgan, Lena isn't her brother. She reached out to Kara to help her stop Lillian. As you might guess, that didn't go so well, prompting Lillian to suit up in Lex Luthor's warsuit via transforming drone and, once suited up, go after Kara and Mon-El (Chris Wood).
The pair were able to defeat Lillian by using her drones against her, and, in the last few moments of the episode, Mon-El is complimented for the idea to which he responds that it was something that he and Brainy had done when they fought Computo. Considering that the Legion has had countless battles in the seven years Mon-El has been in the future, it would be easy to dismiss the mention as just a random villain from the 31st century, but this is Supergirl. There are no easily dismissed references. Legion of Super-Heroes fans will tell you that is especially true for Computo.
For those who haven't quite finished their Legion of Super-Heroes reading list just yet, Computo is a classic villain for the team. Originally created by Brainiac 5 as a mechanical assistant, Computo goes rogue and becomes homicidal instead, and attempts to start an uprising of machines. Computo creates an army of replicas and uses them to spread terror. When Computo realizes (through calculation -- Computo is a machine after all) that the Legion is going to confront it, it redesigns itself into an ultimate form called Computo the Conqueror, sends a distress signal to bring the Legionnaires to Earth, and then creates a weapon that neutralizes the Legionnaires' powers, forcing them out of Metropolis and killing one of Triplicate Girl's bodies in the process.
While on Supergirl Mon-El says that he and Brainiac 5 used Computo's own tech against it, in pre-Crisis comics Brainiac 5 actually defeats Computo using an anti-matter device, but it's not the last the heroes see of the murderous machine. Brainy later reuses some of Computo's original circuitry, leading to it possessing the mind of Legionnaire Danielle Foccart among other resurrections over the years.
As for Lillian, once she is defeated by Mon-El's clever use of her drones, she's taken away on a gurney, and presumably, to jail. At least until next time.
Supergirl airs Mondays at 8/7c on The CW.