The late star first met with Nolan when the director was interested in casting him as the titular superhero in 2005 blockbuster Batman Begins, but the filmmaker reveals Ledger was not at all interested.
He tells movie blog IndieWire.com, “He was quite gracious about it, but he said, ‘I would never take a part in a superhero film.'”
The 28 year old changed his mind upon seeing the final project and later asked to play supervillain The Joker in The Dark Knight.
Nolan continues, “Heath spent months and months (preparing); we cast him even before the script was written so he had a very long time to obsess about it, think about what he was going to do, to really figure it out… It was a very scary moment, because… if he didn’t like (the screenplay), it would have been extremely uncomfortable. But he (liked it). He sighed with relief, I sighed with relief.”
Ledger died of an accidental overdose on 22 January, 2008 just before the movie was released. His performance went on to win him an Oscar for Best Supporting Actor in 2009.