As it could be expected given her history, Mon-El's return to Kara on Supergirl (series developed in part by: Ali Adler) was filled with heartbreak. That said, he did bring with him an exciting element from DC comics that could lead to some more new heroic faces. Will Supergirl add more Legion of Super-Heroes members? The remaining members of the team could make an appearance at some point.
Upon Mon-El's return, we learned that he created this Legion in Kara's legacy with Saturn Girl, his ultimate wife, in the 31st century. The group went through a wormhole (Mon-El's second, considering that's how he got there in the first place) and ended up several thousand years in the past. Then on their return journey back to the future their ship got intercepted and landed back in 2017. It's the kind of happy coincidence that can only happen in comic books and soap opera, don't you think? Anyway, they're here now.
"The governments were overwhelmed by violence," Irma, also known as Saturn Girl, said about the group's origin in a previous episode. "By chaos. Mon-El organized us and we banded together to help Earth's leaders keep the peace — at home and in the stars."
Brainiac-5 and Saturn Girl are the two current characters that Mon-El has recruited at this time — but other members of the 31st Century squad could show up. After all, the Legion has a lot more members in the comics.
Here are some Legion members from the comics that could show up in the future, now that this team has been established on the CW series.
Sometimes known as Polestar, this founding member in the comics has electromagnetic powers. He and Supergirl also had a brief romance. Just putting that out into the Arrow (co-executive producer: Beth Schwartz) 'verse.
The Legion's other founding member in DC lore is this alliterative hero who also sometimes goes by Live Wire — meaning yes, Garth Ranzz shares a name with a DC villain who has appeared on the CW series already.
There's also a Lightning Lass on the team in certain iterations as well. Her name is Ayla Ranzz, and she's Garth's sister. She is bisexual, and romantically involved with fellow Legionnaires named Shrinking Violet and Timber Wolf (who seems a lot like a more lupine version of a certain Hugh Jackman character) at different points in the comics.
The aforementioned girlfriend of Ayla is Salu Digby, who can make herself tiny. As the pun of her name (Shrinking Violet) might indicate, she was shy growing up — which makes for an interesting hero.
Tinya Wazzo was the fifth member to join the Legion in DC comics. She's a spy sometimes, and has the supernatural ability to phase. She was also in a girl group with Super Girl, Saturn Girl, and Triplicate Girl.
Phantom Girl's boyfriend in the comics is this Legionnaire, Jo Nah, who has a bunch of powers but can only use one at a time. As far as weaknesses go, that isn't terrible.
Kara would be excited to meet this hero, as she hails from the cinnamon-smelling planet Starhaven. She has supernatural navigation powers, which is incredibly cool — though in this particular story arc, wouldn't make a lot of sense for the lost team. Dawnstar would know to avoid wormholes.
Finally, this twist may have already been predicted by the latest crossover with The Flash (director: Millicent Shelton, three episodes). Remember that cater waiter who seemed way too excited to be at Barry and Iris' wedding? Maybe she was their granddaughter Jenny Ognats, a Legionnaire known as XS, and she somehow skipped away from her team to do a little genealogical sight-seeing.
There are so many possibilities for this group. Hopefully Supergirl (writer: Caitlin Parrish) will take advantage of all these potential characters for episodes to come.