AceShowbiz - Actor Marc Maron is reportedly in talks to join Joaquin Phoenix in the new 'Joker' origins movie.

The "GLOW" star is in negotiations to play a talk show agent who has a hand in accelerating the titular supervillain's drive into madness, according to Variety.

If he signs on, Maron will feature alongside Robert De Niro, who will play the chat show's host.

Casting on the Warner Bros. movie has been moving swiftly since June, when studio bosses announced that Phoenix would play Batman's arch nemesis in the DC Comics film, following in the footsteps of Jack Nicholson, Heath Ledger and Jared Leto.

Todd Phillips, the director of The Hangover comedy franchise, is taking charge of the "Joker" film from a script he co-wrote with Scott Silver.

In addition to Maron and De Niro, "Deadpool 2" star Zazie Beetz has been attached to play a single mother who draws the attention of the Joker before he turns evil, while The Wrap has reported that "Six Feet Under" actress Frances Conroy is in talks to play the Joker's mother.

Production is set to begin in New York City in September, ahead of an October, 2019 release.

Meanwhile, Leto, who portrayed the villain in 2016's "Suicide Squad", is also set to reprise his role in a standalone spinoff.

Phoenix has previously discussed Leto's work as the Joker and revealed he would take the character in a different direction than his predecessors.

"I think that genre, comic books, kind of lends itself to having different people play the same character and interpret it in a different way," he told Collider. "It's kind of built into the source material in some ways. I think it's cool when people do that."