Williams wound up winning the Oscar for Best Supporting Actor with the part.
One of the most beloved movies of all time is the 1997 drama Good Will Hunting, which was written by and stars Ben Affleck and Matt Damon and features Robin Williams in arguably his most acclaimed role.
Playing Dr. Sean Maguire - the therapist of troubled young genius Will Hunting (Damon) - Williams wound up taking home the Oscar for Best Supporting Actor with the part.
That said, while it's difficult to imagine the movie with anyone but Williams in the iconic role, Affleck and Damon have revealed they once had another actor in mind for Dr. Maguire - two-time Oscar-winner Robert De Niro.
Appearing on The Bill Simmons Podcast together to promote their biographical sports drama Air, the host spoke to the pair about the golden age of American indie cinema in the '90s.
Good Will Hunting
On this, Affleck told the programme: "That was what inspired us... Spike Lee, Quentin [Tarantino], you could make She's Gotta Have It or Slacker, Rick Linklater's movie."
Damon then added: "When we wrote the Robin Williams part, we called it 'the Harvey Keitel part' because of Reservoir Dogs, because we knew that that movie got funded because Harvey said he'd do it.
"So, we literally had this role. His [character's] name was Robert for a long time because we thought we'd want Robert De Niro if we could get him and then we changed it to Sean."
Affleck also told Simmons that anytime he or Damon got cast in a movie with a big star, they would consider offering them the part.
"I remember there was one actor that Matt went to work with and we had really high hopes," the Batman actor explained.
"I called [Damon] on location the next day and I was like: 'So, how's it going'. I hear: 'I don't think he's going to do our movie.'".
You can check out the trailer for Affleck and Damon's new movie Air below.
