The CW superhero series are known for their cross-over episodes and the upcoming mash-up of superheroes from DC is in for something big. A group of alien race will appear as villains in four DC superhero series in CW.

CW is further expanding the universe in their TV superhero series. The network known for bringing the DC comic book series to life is bringing in more villains to the mix which should push the boundaries of the story of each superhero. According to Deadline, the superheroes of CW will face off against an alien race called Dominators.

The Dominators are relatively unknown especially for casual comic book fans. The villains first appeared in the 60s and they are known for also appearing in various crossovers in comic books released during those years. They attack the Earth and the superheroes band together in order to defeat the villain.

The aliens appearing in the series will also require multiple crossover episodes. According to TV Line, CWs "The Flash," "Arrow," "Legends of Tomorrow" and "Supergirl" will each have an episode where they deal with Dominators. Of course, these heroes will appear as a crossover where they eventually help each other and defeat Dominators.

The presence of Dominators in the DC's superhero series should pose serious challenge to superheroes. The alien race is known for genetic manipulation and if the series follows the original concept of the villains, their reason for invading earth is to extract the superhero gene. The superheroes are not just fighting to save the earth - they are literally fighting for their gene.

While the plot of each episode and the general storyline of the crossover is still unknown, fans don't have to wait long before the adventure of superheroes are revealed against the aliens. "Flash" starts the superhero crossover on Oct. 4 with "Arrow" premiering the next day.  On the other hand, "Supergirl" flies to the TV screen on Oct. 10 and "Legends of Tomorrow" will air its first episode on Oct 20.

Dominator against the heroes of DC should be an interesting concept for crossover. The TV adaptation should provide various perspectives on how a hero fights a villain on his/her own and eventually with other superheroes.