Damon, 44, and childhood friend Ben Affleck, 43, co-wrote and co-starred in the 1997 drama film Good Will Hunting, which featured Williams as Damon's title character's therapist. All won their first Oscars for their work on the movie; Damon and Affleck won the Academy Award for their original screenplay while Williams, who died at age 63 in 2014, received one for his supporting performance.
In an interview with E! News carried out before the film's release, Damon recalled how Williams made him and Affleck cry tears of joy.
"It was the very first day of shooting and Ben and I went to the set. We weren't working that day and we just saw them rehearse and we were kind of sitting off to the side of the camera...by the time they said, 'Action,' tears were just falling down my face," he said. "I couldn't believe it. I was just looking at Robin start to speak and say these words that Ben and I had just worked on for five years and I just looked up at Ben and the same thing, he was just..."
"And Robin was great. After the scene ended, he came over to us and he saw us," Damon continued. "He put his hand on our head and just said, you know, 'It's not a fluke. You guys really did this. You really did it."
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After Williams' death, Damon and Affleck issued emotional statements about their friend.
"Thanks chief—for your friendship and for what you gave the world," Affleck wrote on Facebook, adding that the actor made his and Damon's "dreams come true."
"Robin brought so much joy into my life and I will carry that joy with me forever," Damon had said in a statement to E! News. "He was such a beautiful man. I was lucky to know him and I will never, ever forget him."
Good Will Hunting was one of the most memorable films for Williams, who had already been nominated for three Oscars for his performances in Good Morning, Vietnam, Dead Poet's Society and The Fisher King.
While Damon and Affleck had appeared onscreen in several movies before Good Will Hunting, it made them even more famous and helped land them more movie roles. Affleck starred in blockbusters such as Armageddon and Pearl Harbor and won an Oscar for Best Motion Picture of the Year for the 2012 movie Argo, which he directed. He can be seen next as Bruce Wayne in Batman v Superman: Dawn of Justice, which hits theaters on March 25, 2016.
Damon went on to star in Saving Private Ryan, Ocean's Eleven and its sequels and most of the Bourne movies. He can be seen next in the sci-fi film The Martian, which is set for release on Friday.