As for Catwoman I think Rachel McAdams will be a solid choice.
As for the Riddler I would suggest that Crispin Glover be this one. Dude can play crazy with the best of them.
As for Clayface I'd say go with Guy Pearce. He's got the acting chops for it. Let a little CGI do the rest.
Something needs to be done to eradicate our memory of Ahnuld as Mr. Freeze. What better actor than Sir Ben Kingsley?
And if they ever decide to expand and add Robin again (I don't hate the character, I'm just not sure if he is a right fit for the Nolan universe) I think Penn Badgley of Gossip Girl fame would be a good selection.
So what do you think? Do I have a future as a casting agent?
