The CW's 'Arrow' made some season 3 waves with the news that dastardly DC villain Ra's al Ghul would show his face as our new big bad, but the hit superhero drama still has a few new characters to add before we learn what actor leads the League of Assassins. In the meantime, 'Medium''s David Cubitt has joined 'Arrow' season 3 in the role of DC's Manhunter, alongside 'NYPD Blue' alum Charlotte Ross as Felicity's mother.

Via The Hollywood Reporter, Cubitt will first appear in the season's third episode "Corto Maltese" as A.R.G.U.S. operative Mark Shaw, one of many to take the "Manhunter" name in DC mythology. 'Arrow''s incarnation at least will cross paths with Diggle in the titular fictional country, and more than likely have a connection to the "Suicide Squad" we've seen utilized in the past season.

Elsewhere, our Felicity flashback episode "Oracle" will have Charlotte Ross in the role of the MIT-graduate's mother, revealed in season 2 exposition to have been a Vegas cocktail waitress, though it isn't known quite yet if the character will pop up in the present, or in the past. Felicity also identified that her father left them at an early age, leading 'Arrow' fans to abundant speculation as to the character's true identity.

Most recently adding J.R. Ramirez as DC superhero Wildcat, 'Arrow' season 3 has also recruited 'Superman Returns' star Brandon Routh in a major recurring role as tech magnate (and likely Felicity love interest) Ray Palmer, better known as DC's "The Atom." Not only that, but '22 Jump Street''s Peter Stormare will act as our new Vertigo, and ‘Real Steel’ star Karl Yune will play Oliver’s flashback Hong Kong handler, along with ‘Sin City‘ star Devon Aoki as comic character Katana.

Both Caity Lotz and Colin Donnell will return for early episodes this season, and we've also got our first full look at Colton Haynes' costume in his new vigilante persona of "Arsenal," as well.

It remains to be seen if 'Arrow' season 3 will deliver any more major castings on the road to its October 8 premiere, but in the meantime watch the latest trailer below, and tell us what you want to see from the DC drama this fall!

More From ScreenCrush