As a slight disclaimer, I think it's more important for people to look at "What does this role require?" rather than "What range does this actor have?". If the actor can bring the character's personality through it doesn't matter (to me anyways) if they're brilliant actors, as long as it's a good representation of the character. And those requirements change depending on the character in question.
The Joker needs a certain kind of actor with a certain range, Flagg, Deadshot, Boomerang, Deathstroke, Black Spider, King Shark, Killer Croc? Not so much.
