Now that the 3rd season of Arrow has been confirmed, I've been thinking of some ideas of who might appear in it. Please Comment. 

Liam McIntyre as Carter Hall (Hawkman):  possibly an old friend of Oliver's during his time on Lian Yu, or maybe his newest enemy? Not to sure as how to introduce him but I know I'd like to see him. 

Oleg Tatkarov as Richard Dragon: a former member of Ivo's crew who became marooned on Lian Yu with Anatoli, Oliver and Sara. After somehow escaping the hellish island, he found his way into the League of Assassins and has become one of their highest ranking members. 

Ko'imi Kuoha as Jade Nguyen (Cheshire): the Chinese Triad's newest inductee, apprentice to China White and an old friend to Roy Harper. (Hinthinthint) 

Elise Gatien as Carrie Cutter (Cupid): a young woman who quickly becomes obsessed with Arsenal (Roy's alter ego; hopefully) that she begins to kill others with her own homemade arrows in an insane effort to get him to notice her. 

Kofi Kingston as Daniel Brickwell (Brick): a prison inmate who was injected with the Mirakuru and the sole survivor of Slade's "army". Now a "free agent", Brick is attempting to become a kingpin of crime.

Ellen Hollman as Zelda Blake-Gaynor (Lady Blackhawk): Ted Gaynor's widow and the newest head of the Blackhawk Protection Squad, who is attempting to kill Diggle to avenge her dead husband, 

Dean Geyer as Chad Graham (Prometheus): another former member of Ivo's crew who was exposed to the Mirakuru and trained by Oliver, Sara, and Anatoli. Somehow surviving and escaping Lian Yu much like Slade, Graham returns to Starling CIty and begins to use psychological warfare in an attempt to expose Oliver as the Arrow (he could be a mix of Prometheus and Onomatopoeia). or as David Drayson (Slingshot): Roy's former best friend who underwent self-training and is attempting to become the "voice of the Glades" by murdering police officers. 

Tamsin Egerton as Suzanne "Cissie" Kingston (Arrowette/Artemis): the daughter of Thea's former archery trainer who's mother was an Olympic archer (a nod to the comics) and has inherited that skill as well. As Thea learns of Oliver's secret, she recruits Cissie's help in order to help her brother. But she may be harboring some secrets of her own. 

Mark Decascos as Ra's al Ghul: the leader of the clandestine League of Assassins who has his eyes on destroyiing Starling City

Lawrence Gover (Sportsmaster), Lester Butchinsky (Electrocutioner), Albrecht Raines, and Hannibal Bates: hitmen for hire that were hired by a mysterious person to get rid of Arrow, Canary and Arsenal. 

Ideas for Flash

Oliver Kieran-Jones as Ray Palmer (Atom): a charming, charismatic and strict molecular engineer at S.T.A.R. Labs who has become the "den mother" to his fellow co-workers after the public disapperance of C.E.O Harrison Wells (Tom Welling).  Aimee Carrero or Daniella Pineda as Valerie Perez: a young intern at S.T.A.R. Labs who becomes interested in the Flash's powers and possibly the man behind the mask as well.  Justin Bartha as Sam Scudder (Mirror Master): S.T.A.R. Labs leading metallurgist whose past is a complete mystery. Almost as mysterious as Thawne's (Rick Cosnett)  Walter Malcolm "Wally" West: Detective West's juvenile delinquent son who is seeking redemption but is at odds with his father due to been on the wrong side of the law