Joaquin Phoenix has officially been cast as the Joker.

Warner Bros. is developing a ''gritty'' origin movie based on Batman's greatest rival from DC Comics, and the Crown Prince of Crime will be back on the big screen with the 43-year-old actor donning the famous face paint.

The Hollywood Reporter notes that filming is set to start in September in New York, with 'War Dogs' filmmaker Todd Phillips directing the script, which he co-wrote with '8 Mile' screenwriter Scott Silver.

The studio has described this iteration of the story as an ''exploration of a man disregarded by society [that] is not only a gritty character study, but also a broader cautionary tale''.

'The Wolf of Wall Street' producer Emma Tillinger Koskoff will work on the movie, alongside executive producer Richard Baratta.

While there is no release date for the project - which is set to be significantly darker than other comic book movies - it's budget is said to be in the $55 million range.

The crime drama take on Joker's origin could even hit the big screen as soon as 2019.

Meanwhile, Warner Bros. is also said to be working on a second Joker movie with Jared Leto reprising his 'Suicide Squad' turn as the Ace of Knaves in a standalone film of his own.

The latest development comes after it seemed The Joker and Harley Quinn - played by Margot Robbie in the 2016 blockbuster - could be getting their own movie, which would delve into their ''messed up'' love story.

Robbie said previously: ''I'm personally a sucker for a love story. In any iteration. I think people enjoy seeing two characters who, in Harley and Joker's case, would die for one another. It's kind of romantic in a messed up way.''