Director Christopher Nolan has paid tribute to Heath Ledger, insisting he was one of Hollywood's most hardworking actors. Nolan - who directed Ledger as the Joker in new movie The Dark Knight - claims the 28-year-old would often work late just to perfect his role in the Batman sequel. The moviemaker also admired the young actor - who was found dead in his New York apartment last week (ends25Jan08) - because he deliberately chose controversial film roles. He says, "Heath was bursting with creativity. It was in his every gesture. He once told me that he liked to wait between jobs until he was creatively hungry. Until he needed it again. "He brought that attitude to our set every day. There aren't many actors who can make you feel ashamed of how often you complain about doing the best job in the world. Heath was one of them." And Nolan says he is devastated Ledger will not be able to see the final product hit the screens later this year (08). He adds, "Now that screening will never be real. I see him every day in my edit suite. I study his face, his voice. And I miss him terribly."