Ever since it was confirmed that Supergirl Season 2 was shifting from CBS to The CW, there has been talk of a four-show crossover between Supergirl, The Flash, Arrow and Legends of Tomorrow. The crossover was ultimately confirmed, and today we have a new trailer and images for the first installment of this four-part crossover, airing in just under two weeks. This footage not only gives us our first look at villainous aliens known as The Dominators, but also reveals the surprising presence of Deathstroke. If that wasn't enough, we also have a clip from tonight's episode of The Flash and new photos from the crossover.

The CW Network debuted this video which shows the The Dominators arriving on Earth, which leads Barry Allen (Grant Gustin) to call for some help. One of the shots in this trailer features a slew of these CW heroes together, under one roof, including Legends of Tomorrow's Nate Heywood (Nick Zano), Vixen (Maisie Richardson-Sellers), Heat Wave (Dominic Purcell) and Atom (Brandon Routh), The Flash's Barry Allen (Grant Gustin), Cisco Ramon (Carlos Valdes) and Arrow's Oliver Queen (Stephen Amell), Felicity Smoak (Emily Bett Rickards) and Diggle (David Ramsey) . As for Deathstroke, this isn't the first we've seen him teased as part of this crossover, even though his appearance may be a bit earlier than some expected.

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Stephen Amell released a slew of photos from the set of Arrow's 100th episode, which is part of this four-night crossover event. One of those images featured the actor sitting on a park bench with Deathstroke, which certainly hinted that he would be involved in the Arrow portion of the crossover, but seeing him in the Supergirl episode could mean that he will be in all four episodes as well. It's possible we may be getting crossover trailers for each show the day after this week's episode airs, so we may be getting much more footage throughout the week. The clip from The Flash features Barry telling Wally West that he was Kid Flash in Flashpoint.

As for The Dominators, these villains have been described as a sinister, technologically advanced alien race who view Earth's tendency to generate super-powered people as a sign that humans may essentially evolve to be genetically superior, leading to their decision to wipe out humanity. The Dominators' story was part of a three-issue comic crossover event dubbed Invasion, which was drawn by Spawn creator Todd McFarlane. Executive producer Marc Guggenheim teased that this four-part crossover is inspired by a late 1980s DC crossover dubbed Invasion, with the Dominators said to be faithful to the original characters created by artist Todd MacFarlane.

Other images that Stephen Amell posted on the set while the 100th Arrow episode was in production featured Supergirl star Melissa Benoist, The Flash star Grant Gustin and Legends of Tomorrow stars Victor Garber, Franz Drameh and Caity Lotz. It isn't known if Supergirl's famous cousin, Superman (Tyler Hoechlin) will be stopping by during this crossover event. Take a look at this new trailer and stay tuned for more on this crossover event, which kicks off Monday, November 28 at 8 PM ET on The CW.

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