Dominators (Arrowverse)

The Dominators are a race of bipedal extra-terrestrial creatures existing on Earth-1 in the Arrow-verse (another version exists on Earth-38). They serve as the main antagonists of the 2016 Arrow-verse crossover "Invasion!".

Past
The Dominators are fearsome aliens with advanced technology who venture across the universe, looking for potential threats. They speak in an alien language, but can communicate with other species through their telepathic powers.

1951
In 1951 on Earth-1, the Dominators learned of the Earth-born meta-humans, the Justice Society of America. They perceived them to be a potential threat, and so, in the town of Redmond, Oregon, a Dominator ship hovered over a track of uninhabited land, idly. Human military troops arrived, but the Dominators subsequently attack them, killing some and taking a few to be probed for information. A truce was maintained between the Earth's leaders and the Dominators afterwards, and they left Earth behind.

The Flash
75 years later, in late 2016, the Dominators became aware of the meta-human population created by Eobard Thawne's particle accelerator accident, causing some of Central City's citizens becoming meta-humans, including Barry Allen/The Flash, who, in early 2016, used his time-traveling powers to save his mother Nora Allen, creating the "Flashpoint" timeline. After he fixed his mistake and restored the timeline, the Dominators came to Earth to find him, fearing that he would use his powers to once again tear apart the space-time continuum.

A Dominator dropship crashed outside Central City, which Barry found. Dominator soldiers poured out of it, allowing them to enact their plans. The next day, Barry brought A.R.G.U.S. leader Lyla Diggle to S.T.A.R. Labs, where she informed Team Flash of the Dominator threat and their attack in 1951. She also got them to listen to a Dominator message intercepted recently, in which they warn people that any action against them as done in the past will be met with punishment. To face their new foes, Team Flash reaches out, contacting Team Arrow in Star City and the Legends team. Barry and Cisco Ramon/Vibe bring Supergirl of Earth-38 over to Earth-1 as well, where she tells them that Dominators from Earth-38 attacked her home-planet Krypton before she was born, taking people and leaving, just like in Redmond. While they prepare to face their foes, the Dominators are shown at a warehouse in Central City with a mind-control device, as one of them makes contact with another Dominator on their mothership, who tells them to bring the human leader, whom they perceived to be the President of the United States. The next day, a Dominator ship flies by an airport and kidnaps him, then returns to the warehouse.

A portion of the heroes go to the warehouse that night, including Supergirl, where they find the President tied-up and needing help. A Dominator appears overhead and speaks to them telepathically, then uses a laser weapon to disintegrate the President. Realizing that this is a trap, the heroes try to attack, but the Dominator activates the mind-control device, and thus they return to S.T.A.R. Labs to attack their comrades. However, Oliver Queen/Green Arrow and Wally West, who recently acquired super-speed, manage to fight them off. Barry lures Supergirl to the warehouse and tricks her into destroying the mind-control machine, freeing them. Just as they return to S.T.A.R. Labs to wrap things up, Ray Palmer/Atom, Thea Queen/Speedy, Sara Lance/White Canary, John Diggle/Spartan and Oliver all disappear in a stream of orange light, having been teleported away.

Arrow
TBC

DC's Legends of Tomorrow
TBC

Trivia

 * Their language was described in the Arrow portion of the crossover as being like that of an ancient Hebrew dialect, suggesting that they have been to Earth before 1951.