Christopher Nolan’s three-hour epic about the United States atomic bomb program features a huge cast of notable Hollywood character actors playing real larger-than-life figures. No one knows the value of a strong actor with a familiar face better than the man tasked with matching the actor to the role, casting director John Papsidera.

A veteran at the job, Papsidera has filled out the room of programs like “Yellowstone” and “The Offer” (about the making of “The Godfather”), as well as a frequent collaborator of “Oppenheimer” director Christopher Nolan. With all those characters how do you even begin to start casting? According to Papsidera, “You start with the big pieces – the tentpole characters – and then build around them”. Today on FilmWeek, John speaks with Austin Cross about what it took to reanimate characters from the past with modern Hollywood actors.