Johnny Depp as Ragnar Danneskjold,
I think he would do an amazing job he has always had the talent to get deep into his characters I think we would all be pleasently surprised.
I don't know why but Brad Pitt was the first person I thought of when I heard about this as well, I think he would make a great John Galt.
Kevin Spacey...nailed that one for sure and Antonio Banderas he would be perfect.
Dagny will be tuff though...I think it would be almost better to not have a big time actor. Maybe an unknown. That way we didn't have this history that we aligned her with...She would just be Dagny.