The crossover already sounds like a must-see TV event. While we don't know anything about the plot, we do know the identity of a certain character who will make her debut in the crossover: Batwoman. News broke on July 17 that The CW and Greg Berlanti are developing the very first live-action Batwoman project. Given that Arrow established the existence of both Gotham City and Bruce Wayne in Season 6, it was likely only a matter of time before a member of DC Comics' Bat-family turned up. I'll be curious to see if Batwoman's story is set on Earth-1 with Arrow, The Flash, and Legends of Tomorrow or on an alternate world like Supergirl.