Crisis on Earth-1

"Crisis on Earth-1" was the planned crossover event between The Flash and The Batman. It was cancelled because it didn't fit in with the continuity of the shows, and 'felt out of place'.

The crossover would have featured several heroes from DC Comics, some of whom have already made their debut in the Flashverse. It was set to air in 2019, with episode 8 of The Flash season 3, and episode 6 of The Batman season 1.