According to Stargirl co-creator Geoff Johns, a crossover between the DC Universe original series and The CW's Arrowverse is only a matter of time.
Asked about the potential for a Stargirl/Arrowverse crossover, Johns told CBR, "We're completely open to it. There's so many possibilities. You know, clearly, we're set on Earth-2, so we're on our own Earth, much like the comic books. We're set on Earth-2, and it gives us the room to tell our history and story, but also the opportunity in the future to do anything in the comic books or to always cross over with other places. Conversations have been had, but it's all of matter of when it makes sense and if we have the best story."
In his statement, Johns also confirmed conversations about a crossover have already taken place. This makes sense, considering The CW picked up broadcast rights to the series prior to its premiere. Now, under that agreement, Stargirl releases a new episode weekly on Mondays on DC Universe, then airs the following Tuesday night on The CW. So, the streaming service and the network are already sharing the series.
What's more, Stargirl was part of the The CW's five-show "Crisis on Infinite Earths" crossover, albeit briefly. After the Seven Paragons restored the Arrowverse's multiverse, the crossover cut to many of the different Earths that were saved in the process. One of those was the new Earth-2, Stargirl's home world. Meanwhile, many other similar universes were combined into one: Earth-Prime, which is now home to Supergirl as well as Arrow, The Flash, DC's Legends of Tomorrow and Batwoman. As a result, "Crisis" set a precedence that would allow Stargirl to cross over with the Arrowverse.
As it stands, the Arrowverse is not planning a major crossover event for next year. Due to the coronavirus (COVID-19) pandemic, the regular fall seasons have all been pushed back to a January 2021 release, where the crossover usually airs in December. Further, Supergirl will be held until midseason to accommodate star Melissa Benoist's pregnancy, which will prevent the show from crossing over with the others. Nevertheless, a mini-crossover between Batwoman and new series Superman & Lois is in the works.
DC Universe's Stargirl stars Brec Bassinger as Courtney Whitmore (Stargirl) and Luke Wilson as Pat Dugan (S.T.R.I.P.E.). The series airs Monday on DC Universe and Tuesdays on The CW at 8 pm ET/PT.