"Legends Of Tomorrow" will likely have three DC characters joining the show and details on the first crossover episode in "Arrow" TV series.
Executive producer Marc Guggenheim tweeted the cover page of "Arrow" season 4 episode 8 titled "Legends of Yesterday", which will likely pave the way for the pilot episode of "Legends of Tomorrow" next year. Cast member Casper Crump also posted a photo of himself in his Twitter account appearing in an episode of "The Flash" season 2 alongside "Arrow" star Stephen Amell indicating that his character, Vandal Savage will also make an appearance in Central City as well.
The episode is said to explore Vandal Savage's (Crump) backstory and number of characters from "The Flash" and "Arrow" shows will appear in the episode such as Oliver Queen/Green Arrow (Amell), Barry Allen/The Flash (Grant Gustin), Prof. Martin Stein/Firestorm (Victor Garber), Sarah Lance (Caity Lotz), Ray Palmer/The Atom (Brandon Routh), Rip Hunter (Arthur Darvill) etc., Vine Report reported.
Aside from the crossover episodes, three DC characters are rumored to appear in "Legends of Tomorrow" and these are Jonah Hex, Roy Harper/Arsenal and Caitlin Snow/Killer Frost.
Jonah Hex in the DC comics is a disfigured bounty hunter and Civil War veteran during the old west and was recruited by the the Lord of Time to join the Five Warriors of Forever to fight the Justice League and the Justice Society. He eventually rebelled against the Lord of Time becoming a hero in the process and has been involved in many storylines that involved time travel within the comics. Jonah Hex has also encountered Vandal Savage numerous times in the comics and it is rumored that he will likely be abducted from his own time period and will likely meet Rip Hunter the rest of the group in future episodes, Moviepilot reported.
Caitlin Snow/Killer Frost on the other hand, "The Flash" actress Danielle Panabaker stated in an interview that her character might get a cameo appearance in "Legends of Tomorrow" due to his connection with Firestorm. The season premiere of "The Flash" season 2 saw Ronnie Raymond's (Robbie Amell) apparent death in the singularity that almost destroyed Central City with Martin Stein surviving and having Jay Jackson (Franz Drameh) as Ronnie's successor to the Firestorm matrix. Ronnie's death could be the catalyst for Caitlin to have metahuman powers and become her villainous alter-ego, Killer Frost.
Lastly, "San Andreas" star Colton Haynes confirmed the the possibility that Roy Harper/Arsenal could return to "Arrow" season 4 and appear in "Legends of Tomorrow" during the AsiaPop Comic Con event in the Philippines hinting that he is just "one call away".
"Legends of Tomorrow" is speculated to premiere in January 2016 on the CW Network.