With production getting under way on Season 4 of Arrow, The CW Network series has just added two new cast members. Access Hollywood reports that Jeri Ryan has signed on to play Jessica Danforth, while JR Bourne has come aboard to portray DC comics villain Double Down. Both actors are signing on for just one episode apiece, with Jeri Ryan appearing in the second episode of Arrow Season 4, and JR Bourne guest starring in the third episode.

Jessica Danforth is a new character who doesn't originate in the DC Comics. She is described as a friend of Oliver Queen's family. The character's political ambitions "put her in the crosshairs of a menacing antagonist." It isn't clear if there are plans for the character to return later on in Season 4 or not. But she could certainly return, especially with her strong connection to Oliver.

JR Bourne's Double Down does have origins in the comic books, but he is more closely associated to The Flash comics. Double Down, a.k.a Jeremy Tell, is a meta-human who has the ability to turn his card-playing tattoos into deadly weapons. Given that The Flash and Arrow regularly cross over, it's certainly possible that this charcter may be pulling double-duty on both shows, but that has not been confirmed.

Related: Supergirl, Flash & Arrow Team Up in The CW's Superhero Sizzle Reel

Jeri Ryan and JR Bourne join a slew of new Arrow stars including Neal McDonough as Damien Darhk, Alexander Calvert as Anarky, Echo Kellum as superhero Mister Terrific and Jimmy Akingbola as the villainous Baron Blitzkrieg. The show's producers also hinted during Comic-Con that they are still trying to bring in Matt Ryan as John Constantine, even though his show was cancelled by NBC. Fans at SDCC also got a glimpse of the new costumes that will be worn by Stephen Amell's Oliver Queen and David Ramsey's Diggle this season.

Jeri Ryan most recently had roles in Helix and Major Crimes. She is best known for playing Seven of Nine on the hit sci-fi series Star Trek: Voyager. JR Bourne is best known for his role as Chris Argent on MTV's Teen Wolf, and he most recently guest starred on USA Network's Satisfaction. What do you think about these new casting additions?