Baldwin is Batman's father.
The Joaquin Phoenix Joker film has found its Thomas Wayne. Thomas is famous in the Batman comic books as Bruce Wayne's father. Thomas' death, alongside his wife, is the catalyst that would push Bruce to become Batman later in life. According to The Hollywood Reporter, Alec Baldwin has been cast as Thomas Wayne in the upcoming Joker film. Since this reiteration of Batman lore is non-canonical, the personality of Thomas has been altered. Sources say instead of being a caring physician and philanthropist, Baldwin will play a stereotypical tanned businessman that will be reminiscent of a 1980's Donald Trump-like character.
Baldwin will join Zazie Beetz and Robert DeNiro in the yet to be titled Joker film. The movie will exist outside of the already established DC Universe that includes Ben Affleck's Batman and Gal Gadot's Wonder Woman. The Todd Philips helmed film will be more of a dark character study than a traditional superhero flick, broadening the way audiences view comic book films. It also has a minuscule budget when compared to Justice League or Batman V Superman, which means you should expect less green screen and CGI, and more interpersonal storytelling. The Joker origin film is set to hit theaters on October 4, 2019.