Superman & Lois has recruited Degrassi: The Next Generation star Stacey Faber to play the role of Leslie Larr, a character newly-created for the TV series but one who might have ties to a Silver Age DC villain. Farber, who played the role of Ellis Nash for seven seasons on Degrassi, will be taking on a tough, cold-hearted character on Superman & Lois. The actress has also appeared in the CW comedy 18 to Life, which had Supergirl veteran Jesse Rath in it, so she's got connections to both the network and to the broader Arrowverse already in place before she shoots a scene.
While there is no such character in the DC canon as "Leslie Larr," the name is likely a nod to the Kryptonian villain Lesla-Lar. That character appeared primarily as an enemy of Supergirl, and hailed from Kandor.
Per the official character description, which debuted at Kryptonsite, the character is "the right hand to one of the most influential people on the planet," and "she's gone from a young, idealistic dreamer to a hardened, world-worn dream killer." Larr is personally described as "athletic, strong…and often times heartless."
With Supergirl officially wrapping its run after the upcoming season, Superman & Lois will be the place where Kryptonian storylines are explored in the Arrowverse. Of course, the flipside of any notion that Leslie is part Kryptonian would be the idea that she is the right hand to a character who sounds suspiciously like it might be Lex Luthor. Even with defeating Superman as a justification, it's difficult to imagine him cozying up to an alien.
Following the events of The CW's "Crisis on Infinite Earths" crossover last season, Superman & Lois will launch in 2021 and centers on Clark Kent (Tyler Hoechlin), Lois Lane (Bitsie Tulloch), and their two sons, who leave Metropolis for Smallville. Superman and Lois have to navigate the challenges of being parents to a pair of teenagers (who might or might not have their dad's super powers) while also being famous world-savers in their own right as the world's most adored superhero and a celebrated investigative journalist, respectively.
Because the series is set after the Crisis, little is really known about the world Superman inhabits. At the start of that event, Superman and Lois only had one son -- an infant -- and so when the timeline was realigned, clearly quite a bit changed. How Leslie Larr plays into that dynamic is yet to be seen, but hopefully fans will get to learn a bit more before the series premieres early next year.