Crisis on Earth-X

Crisis on Earth-X is the name of the upcoming 4 part crossover event between Supergirl, Arrow, The Flash and DC's Legends of Tomorrow. The crossover will air over two nights from November 27th to November 28th, 2017. The episodes that are involved in the crossover are:
 * TBA (Supergirl)
 * TBA (Arrow)
 * TBA (The Flash)
 * TBA (DC's Legends of Tomorrow)

Trivia

 * Earth-X is a world where Germany won World War II and Green Arrow, The Flash and Supergirl are evil. It was first referenced in the Supergirl episode.
 * Earth-X is the main setting for upcoming series Freedom Fighters: The Ray.
 * The Ray will make an appearance in the crossover.