Christopher Nolan calls picking Downey for 'Iron Man' among the best casting decisions "ever made"

With news the Oscars will soon be giving kudos to the people who help pick the stars for a given project comes praise from Oppenheimer director Christopher Nolan on what he calls "one of most consequential casting decisions ever made."

That honor goes to picking Robert Downey Jr. as Tony Stark in 2008's Iron Man, Nolan told Stephen Colbert on Thursday night's The Late Show.

While he's now the odds-on favorite for his first Oscar for Nolan's Oppenheimer, back in September of 2006, Downey was a risky proposition to lead what would become the Marvel Cinematic Universe, following years of legal trouble and addiction.

Director Jon Favreau and casting director Sarah Halley Finn pushed for Marvel Studios to screen test Downey, and the rest is history.

"I've always wanted to work with him," Nolan expressed to Colbert, adding, "He has such charisma, and I think him playing Tony Stark in Iron Man is one of the most consequential casting decisions ever made in the movie business."

Nolan explained that Downey has "this incredible generosity of spirit." He added, "It means when he's in a scene with other people he's making sure they are all doing their best ... He's helping them clarify those emotional connections."

The filmmaker noted he was keen to have Downey shed Stark in playing his Oppenheimer character Lewis Strauss. "I wanted to give him the opportunity to lose himself in a part, lose himself in another human being the way that great actors love to," Nolan said.