Robert De Niro is reportedly in talks to join the cast of the Joker standalone movie.

The Hollywood veteran could star alongside Joaquin Phoenix, who is playing the iconic villain, in the much-anticipated Warner Bros. and DC film.

De Niro, 74, is being eyed for the role of a talk-show host who is key to the Joker's origin, according to The Hollywood Reporter.

The standalone movie is said to have been handed a budget of $55 million, which is less than most DC or Marvel comic book films.

Insiders claim the production will look to steer clear of the non-stop fighting that has characterised other movies in the genre, and will instead focus on character exploration.

Meanwhile, Joaquin recently teased that his portrayal of the villain - known for his pale face and scary red lips - would be ''unique''.

The 43-year-old actor said: ''I wouldn't quite classify this as like any genre. I wouldn't say it's a superhero movie, or a studio movie or a ... It feels unique, and I think more then anything, and probably the most important thing, is Todd [Phillips, the director] seems very passionate about it and very giving, and so that's exciting.

''I think, underneath the excitement of these films, and the size of them, there are these incredible characters that are dealing with real life struggles. And sometimes that is uncovered and exposed, and sometimes it isn't, and so I always felt, like, there were characters in comics that were really interesting and deserve the opportunity to be kind of studied. And so I think that's what Todd sees appealing about this idea.''