But that picture is not exactly… wild.
On Sunday, Todd Phillips, director of the yet-to-be-titled Joker movie, posted a picture of Phoenix on Instagram, with the caption "Arthur". Arthur is presumably the name of the Joker before he became the Joker.
In the comics, there's no definitive backstory for Batman's greatest villain. This origin story is written by Phillips (who directed the Hangover trilogy) with Scott Silver, a co-writer on 2010's The Fighter.
The story will be a character study as well as a cautionary tale of "a man disregarded by society who becomes the ultimate supervillain," according to Deadline.
The cast confirmed so far includes Robert De Niro, Zazie Beetz, Frances Conroy and Marc Maron. There was speculation Alec Baldwin had signed on for a role, but that has since been debunked by the actor himself.
For more, here are some set photos from New York, shared on Twitter by pop culture site Just Jared:
Warner Bros. is working onstarring Jared Leto, who took on the role for . That film doesn't have a release date yet.
The yet-to-be-titled Joker movie starring Joaquin Phoenix is set to crash into theatres.
First published Sept. 16 at 8:05 p.m. PT.
Update, Sept. 17, 5:10 p.m.: Adds information on confirmed cast and set photos.