The late Heath Ledger's unique take on the anarchic and sadistic Clown Prince of Crime in The Dark Knight has resonated with fans since it first hit screens all those years ago.
Looking back on the actor's approach to playing the legendary villain, The Dark Knight Trilogy's creator Christopher Nolan has reflected on his "unpredictable" and "extraordinary" work.
Speaking to BBC Radio 1, Nolan said that he was "very proud" to have been involved with Ledger's performance, and his eventual posthumous Oscar win for Best Supporting Actor.
"I took huge pride in having been in any way involved with this great performance, this legacy. He was an extraordinary person and an extraordinary actor," he explained.
"For him to be recognised in that way, I think, it was very meaningful for his family and meaningful, I think, for film history that what he contributed... be marked in that way."
Remembering Heath's immersive and unpredictable embodiment of the Joker, he said: "A lot of what Heath did, he would discuss with me, but... he'd give me hints about what he was going to do, or we would talk about it a bit.
"I would try and be an audience for him or sort of gauge with him what he was doing, but a lot of it was about unpredictability, and I think he wanted to play his cards a little close to the chest."
He continued: "He would very gradually reveal to me the voice and the way he was going to do things, but not in one go... We watched him develop it with the wardrobe and the make-up and everything."
Focusing on the voice, Nolan said: "[It] was so unpredictable, he created this bizarre pitch. I've seen a lot of people try to imitate it since; you never knew whether he was going to go high or he was going to go low, you never knew what that guy was going to do, and that was what was terrifying about him."
