'Crisis on Earth-X': Check out photos from The Flash, Supergirl, Arrow, and Legends of Tomorrow crossover

The CW's four-way crossover is upon us! Airing across two nights starting Monday, Nov. 27 at 8 p.m. ET, the superheroes of The Flash, Arrow, Supergirl, and DC's Legends of Tomorrow unite to take on the villains of Earth-X. Here's what's in store: "Barry and Iris’s wedding brings the gang together, but things go awry when villains from Earth-X attack the ceremony. All of the superheroes band together with help from their super friends like Citizen Cold, The Ray, Felicity Smoak, Iris West and Alex Danvers to take on their most formidable villains yet. Earth’s mightiest heroes – Green Arrow, Supergirl, The Flash and White Canary – lead their teams into battle to save the world."