A lot of cast announcements have recently been made for both The Flash and the third season of Arrow, namely Robbie Amell (Stephen Amellís cousin and star of the now defunct Tomorrow People) who will play Firestorm in The Flash and Brandon Routh as The Atom in Arrow. With the explosion in Central City we are really going to start seeing some super-powered heroes and villains. Which hero or villain from the DC universe would you love to see enter the Arrow/Flash universe?
I would love to see Nightwing, I think that would be cool. For villains, Harley Quinn - who was hinted at already - would be awesome, but Lex Luther would also rock. Actually, I would love to see Queen vs the Joker, complete geek epicness!
Arrow is very popular but really aims towards those who love superhero action/adventure shows, so although popular, it won't appeal to everyone. The Flash is technically a spin-off of Arrow, but it looks to be a very different kind of show, still a superhero action/adventure but much lighter and comedic.