DC on the CW: 2017 crossover is called "Crisis on Earth-X" and begins on November 27

Finally revealing what the plans are for this year's annual DC on the CW crossover is, a spectacular comic book cover poster was revealed by DC Entertainment and The CW to announced "Crisis on Earth-X" -  the two-night special crossover event that will happen between Arrow, The Flash, DC's Legends of Tomorrow, and Supergirl on November 27 and 28. Moving from its new Thursday timeslot, Arrow will be the headliner show beginning the crossover with Supergirl continuing things on November 27th, while Legends of Tomorrow and The Flash finish things off on the 28th.

Evoking "Crisis on Infinite Earths" and the numerous DC crossover events, this is DC on the CW's biggest looking comic-esque crossover to date. While the plot is still shrouded in mystery, all that's known is that alternate evil versions of the heroes hailing from Earth-X, who crash the wedding of Barry Allen and Iris West. Also appearing is The Ray, who is the star of a new animated series called "Freedom Fighters: The Ray" which will premiere on The CW.

With the cover drawn by Phil Jimenez, the producers of The CW's slate of DC shows told what inspired them to create this crossover (as posted on Comic Book.com)

“We conceived this year’s crossover to be evocative of the annual Justice League/Justice Society crossovers we grew up with and looked forward to as kids," said executive producers Andrew Kreisberg and Marc Guggenheim in a statement. "Phil was the perfect choice to bring the comic book cover iteration of this idea to life. You can count on one hand the number of artists who could compellingly represent so many characters in a single image. Phil is one of them. And his design invokes the cover of Justice League #207, which was the 20th Annual JLA/JSA crossover. Our ten year-old selves are in heaven.” 

"Some of the first DC Comics I ever read were those insane crossovers with a dozen characters from alternate earths and dimensions -- the kind of stuff I later became known for!" Jimenez said. "So when CW asked me to do an homage cover inspired by those amazing team up covers, I couldn't resist, the chance to draw all of The CW’s DC Super-Heroes in one crazy action sequence was insanely fun and exciting. And Romulo Fajardo'a colors brought everything to life!”