In spite of some speculation that The CW's interconnected universe of DC Comics adaptations might take a year off from line-wide crossover events following this season's multiverse-shattering "Crisis on Infinite Earths," Arrow co-creator Marc Guggenheim, who serves as showrunner on the crossovers, told fans on Twitter today that the writers and producers already know what their next one is going to be. He stopped short of giving any other clues as to what the crossover -- which is likely to take place in late November or early December 2020, if the past is any guide -- will be, leaving fans to speculate in the comments.
There are some DC crossovers that seem pretty obvious...but that has not historically been a great indicator of what will actually happen. Almost nobody guessed that "Crisis on Earth-X," "Elseworlds," or "Invasion!" would be the crossover events the years they happened.
You can check it out below. Our favorite response is DC's Legends of Tomorrow star Caity Lotz replying with "Wait, we do?!"
We already know what next year's crossover will be. https://t.co/qru4Rf9KOX— Marc Guggenheim (@mguggenheim) March 12, 2020
The first-ever crossover came way back when The Flash and Arrow were the only shows on The CW. Titled "Flash vs. Arrow," the two-part story pitted the pair against villains from both of their existing rogues galleries.
Next came "Heroes Join Forces," which served as a backdoor pilot for DC's Legends of Tomorrow, and pitted Rip Hunter, Hawkman, Hawkwoman, and the heroes of Arrow and The Flash against Vandal Savage.
The following year, Supergirl joined the fun in "Invasion!," which introduced the first aliens -- an invasion of Dominators -- to Earth-1. The Flash, who had appeared in an episode of Supergirl, recruited her to help the heroes of Earth-1 figure out how to deal with alien threats.
The year after that, "Crisis on Earth-X" saw Barry Allen and Iris West's wedding crashed by evil doppelgangers of the Arrowverse heroes from an alternate Earth where the Nazis won World War II and Oliver Queen became the Fuhrer. They hoped to kidnap and dissect Supergirl in order to give a heart transplant to their version of Kara Zor-El, but failed and ultimately both Barry and Iris and also Oliver and Felicity got married.
Then came "Elseworlds," where The Monitor was testing The Flash and Green Arrow to see if they were fit to aid him in the coming Crisis. He gave a the reality-warping Book of Destiny to a villain who, among other things, swapped Oliver and Barry's powers minds so that each had to figure out how to function as the other. That story led directly into the events of "Crisis on Infintie Earths," which brought together all of the DC shows on The CW as well as numerous cameos from past movies and TV series including Smallville, Superman Returns, Batman, and 1990's The Flash.
With The CW unlikely to have a traditional upfront presentation in May, fans might have to wait until the summer (or even later) to get a firm idea of what the crossover might be.