Crisis on Earth-X

Crisis on Earth-X is the name of the fourth Arrowverse crossover between, , ​​​​​ and. It began November 27, 2017, and finished on November 28, 2017.

Synopsis
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.

Cast

 * Stephen Amell as Green Arrow (Oliver Queen) / Dark Arrow (Oliver)
 * Tala Ashe as Zari Tomaz
 * Melissa Benoist as Supergirl (Kara Danvers) / Overgirl (Kara)
 * Paul Blackthorne as Sturmbannführer
 * Mehcad Brooks as Guardian
 * Christina Brucato as Lily Stein
 * Tom Cavanagh as Harry Wells / Reverse-Flash (Eobard Thawne)
 * Colin Donnell as Prometheus (Tommy Merlyn)
 * Franz Drameh as Jefferson "Jax" Jackson / Firestorm
 * Victor Garber as Martin Stein / Firestorm
 * Rick Gonzalez as Wild Dog (Rene Ramirez)
 * Grant Gustin as The Flash (Barry Allen)
 * David Harewood as John Jones/Martian Manhunter (J'onn J'onzz)
 * Juliana Harkavy as Black Canary (Dinah Drake)
 * Isabella Hofmann as Clarissa Stein
 * Jeremy Jordan as Winn Schott / General Schott
 * Echo Kellum as Mister Terrific (Curtis Holt)
 * Jessica Parker Kennedy as Nora West-Allen
 * Chyler Leigh as Alex Danvers
 * Keiynan Lonsdale as Wally West
 * Caity Lotz as White Canary (Sara Lance)
 * Jesse L. Martin as Joe West
 * Wentworth Miller as Citizen Cold (Leo Snart)
 * Danielle Nicolet as Cecile Horton
 * Danielle Panabaker as Killer Frost (Caitlin Snow)
 * Candice Patton as Iris West
 * Amy Louise Pemberton as Gideon
 * Dominic Purcell as Heat Wave (Mick Rory)
 * David Ramsey as Spartan (John Diggle)
 * Emily Bett Rickards as Felicity Smoak / Felicity
 * Brandon Routh as The Atom (Ray Palmer)
 * Patrick Sabongui as David Singh
 * Maisie Richardson-Sellers as Vixen (Amaya Jiwe)
 * Russell Tovey as The Ray (Ray Terrill)
 * Carlos Valdes as Vibe (Cisco Ramon)
 * Chris Wood as Mon-El
 * Nick Zano as Steel (Nate Heywood)