Alec Baldwin is set to star in 'Joker'.

The 60-year-old actor is said to be in line to portray Thomas Wayne, the physician and philanthropist father of Bruce Wayne/ Batman, who will be played by Joaquin Phoenix in the hotly-anticipated movie.

According to Deadline, Baldwin's role is yet to have been announced by Warner Bros., but he is expected to take on the part of Thomas, who, along with his wife, is shot outside the theatre, a tragic event which Bruce witnesses, igniting his path to becoming a vigilante.

Wayne's killer was initially hitman Joe Chill in the early 'Batman' comics, but in the superhero's 1989 movie the Joker was the aggressor.

Filming is due to start on September 10 and Todd Phillips is to direct the motion picture, which will also star Robert De Niro, Marc Maron and Frances Conroy.

Phoenix recently admitted his portrayal of the Joker would be ''unique''.

He 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 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.''

'Joker' is scheduled for release on October 4, 2019.