In the show, Saturn Girl, aka Imra Ardeen, was born on Saturn's moon, Titan, and arrives on Earth to help out Supergirl with her telekinetic powers. In the comics, Saturn Girl first appeared in the 1958 Adventure Comics #247. She went on become the founder of the Legion of Super-Heroes and was the first female to lead a comic book super-team. Maybe this is a sign that the Legion of Super-Heroes is about to make a big entrance. (Check out my colleague Lucas Siegel's in-depth analysis of why it is time to bring the Legion to life.)
According to Variety, Saturn Girl arrives in National City "just in time to help Supergirl (Melissa Benoist) face one of her biggest threats." Is that "big threat" new baddie Reign? Last year's big bad, Rhea, was killed at the end of last season, so she's out. Is there another threat out there that still hasn't been defeated? Could this be another, one-or-two episode "threat?"
This isn't the first time Saturn Girl has been brought to the small screen. She was played by Alexz Johnson in an eighth season episode of Smallville, in which she teamed up with other Legion members Cosmic Boy and Lightning Lad. Saturn Girl was also animated in episodes of Superman: The Animated Series and Justice League Unlimited, and was a lead character in the animated series Legion of Super-Heroes.
Supergirl returns to the CW on Oct. 9.