While the Arrowverse has finally introduced Gotham City and its various locales and characters in this year's DCTV crossover "Elseworlds" on The CW, the Batman himself is still off-limits to the shared television universe.

While promoting the crossover, Arrow showrunner Beth Schwartz revealed that references to the Dark Knight-side of the DC Universe were initially restricted by Warner Bros. and DC Comics, save for a passing reference to Bruce Wayne and Ra's al Ghul and his daughters appearing on Arrow with the League of Assassins.

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"We tried so many times," admitted Schwartz in an interview with TheWrap. "It was kind of shocking.”

Years of persistence have paid off, with Gotham figuring prominently in the crossover and packed with all sorts of Easter eggs and nods to the mythos while establishing that the first Arrowverse vigilante is Batman. Despite this, Warner Bros. currently remains firm that the Dark Knight will not actually make an appearance.

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"That’s the one where they cut you off," confirmed Schwartz. "Slowly but surely, we’ll just keep picking away at it.”

This year's Arrowverse crossover event will involve the casts of Supergirl, Arrow, and The Flash. The event will unfold over three nights, starting with a special episode of The Flash on Sunday December 9 at 8 pm ET/PT. Then, it continues Monday, December 10, with Arrow, and concludes on Tuesday, December 11, with Supergirl.