Joaquin Phoenix almost played the Joker in 'The Dark Knight'.

The 50-year-old actor was approached by Christopher Nolan to play the Batman villain in the 2008 picture but turned the part – which went to the late Heath Ledger – down as he felt he "wasn't ready" for such a role at the time.

Phoenix told the 'Tetragrammaton with Rick Rubin' podcast: "I remember I talked to Chris Nolan about 'The Dark Knight' and that didn't happen for whatever reason.

"I wasn't ready then. That's one of those things where it's like, 'What is in me that's not doing this?' And it's not about me. There's something else.

"There's another person who's going to do something... I can't imagine what it would be if we didn't have Heath Ledger's performance in that film, right?"

The 'Napoleon' actor added: "I don't know whether Christopher Nolan was coming to me saying, 'You're definitely the person.' I can't remember the context of how we met, but I know we met.

"My feeling was I shouldn't do this, but maybe he was also like, 'He's not the guy.'"

Phoenix eventually did get to play the Clown Prince of Crime in the Todd Phillips movie 'Joker' in 2019 – winning the Best Actor Oscar for his portrayal – but Warner Bros. executive Jeff Goldstein admitted the musical sequel 'Joker: Folie a Deux' "didn't land" with audiences after it flopped at the box office despite the addition of Lady GaGa to the cast as Harleen 'Lee' Quinzel.

Speaking to The Wall Street Journal newspaper, Goldstein said: "The movie didn’t land with audiences the way we wanted it to."

Meanwhile, Phillips suggested that he was unlikely to return to the world of 'Joker' for a third movie.

The filmmaker told Variety: "For me, I’ve always thought that these two movies kind of exist as their own thing.

"And, no. I know you’re trying to get the next thing, but I don’t want to go into that."