Back in November, Supergirl co-creator/executive producer Greg Berlanti teased that it may be possible for his upcoming CBS superhero series to cross over with his CW shows Arrow and The Flash, despite airing on different networks. Marc Guggenheim, who also executive produces both Arrow and The Flash, revealed in a wide-ranging interview that "it's possible" a crossover could happen. While this hasn't been confirmed, The Hollywood Reporter also reveals that language has been written into Greg Berlanti's CBS contract that would allow the crossover. Here's what THR's Lesley Goldberg had to say.

"I actually heard it's in Greg's deal, that Supergirl can cross over with Flash and/or Arrow."
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What makes this crossover scenario much more plausible is the fact that The CW is owned by both CBS and Time Warner, the parent company of Warner Bros. and Warner Bros. Television that produces Arrow and The Flash. While it's incredibly rare to see any type of crossover between two different networks, it seems Greg Berlanti has found a way to make it work, although it isn't clear when Supergirl will even debut yet. In case you're hoping for more possible DC Comics crossovers on shows like Fox's Gotham and NBC's Constantine, there is hardly any chance of that happening since they all have different producers and don't have the same connections at two networks that Greg Berlanti now has.