'Legends of Tomorrow’ cast, trailer, premiere & spoilers: 'The Canary' leaves 'Arrow' for good

DC Superhero fans will be in for an awesome treat this coming December as two of The CW Network's popular comic-inspired hit TV series, "Arrow" and "The Flash," will be doing another crossover episodes, which the shows' execs intend to do in an annual basis.

The temporary merge was set up in order to pave the way for the launch of CW's upcoming installment DC's "Legends of Tomorrow." The "Flash" episode for the crossover will be entitled "Legends of Today" and will air on Dec. 1 while the "Arrow" crossover episode called "Legends of Yesterday" will be shown on Dec. 2.

American writer and producer Phil Klemmer, who was tapped by creator Greg Berlanti to do the executive producer/showrunner role for 'Legends of Tomorrow, talked about the "Flash" and "Arrow" crossover during the October 2015 Comic Con in New York, ComicBookResources wrote.

"What we've planned is kind of nuts. There were crossover episodes last season, and now we've doubled down on the notion of trying to integrate the worlds of the three shows," he said.

"It's such an awesome idea on paper, but logistically, when you try to figure out what it means for these poor actors trying to appear on three shows at once -- time travel is something that makes your head want to explode."

Klemmer believed that if the idea works it could be one of the coolest things because viewers have not seen this anywhere else on TV and, in a way, it enriches the world of all of the shows.

The cast of "Legends of Tomorrow" will include some new and familiar faces with the likes of Brandon Routh as Ray Palmer aka The Atom, Caity Lotz as Sara Lance aka White Canary, Falk Hentschel as Carter Hall aka Hawkman, Ciara Renee as Hawkgirl and Arthur Darvill as Rip Hunter.

Caster Crump will be playing the role of Vandal Savage, the main villain in the show. The "Prison Break" duo of Wentworth Miller (Captain Cold) and Dominic Purcell (Heat Wave) will also be part of the show, but this time on the superhero side.

Meanwhile, Sara Lance whose presence has been on and off in "Arrow" will also make her own crossing over. The fans may not be seeing her in the series for a while because Sara is set to join his haphazardly assembled team in "Legends of Tomorrow" as the White Canary.

"She's a wanderer, she's a little bit of a gypsy. She has that in her soul where she never quite feels at home. That keeps driving her away. Hopefully they know her well enough that they would be accepting of it," Caity Lotz said on her character.