Good Will Hunting is a 1997 American drama directed by Gus Van Sant, starring Matt Damon, Robin Williams, Ben Affleck, Minnie Driver, and Stellan Skarsgård. The story follows Will Hunting (Damon), a troubled janitor at MIT with extraordinary mathematical abilities, whose genius is discovered by Professor Lambeau (Skarsgård). Caught for assault, Will is given a choice between jail and therapy, with the latter connecting him to psychologist Sean Maguire (Williams).

Matt Damon initially began work on the story as an assignment for a playwriting class at Harvard University, submitting a 40-page script inspired by themes of genius and trauma. Damon’s college friend Ben Affleck helped expand it into a feature-length screenplay, originally conceived as a thriller where Will is targeted by government agencies. Rob Reiner, then at Castle Rock Entertainment, advised them to focus less on the thriller aspect and more on the emotional core—the mentor-mentee relationship between Will and his therapist.

After Castle Rock stalled, Affleck approached Kevin Smith (then working with him on Mallrats and Chasing Amy), who introduced the duo to Miramax’s Harvey Weinstein. Weinstein agreed to let Damon and Affleck star, and the final film was directed by Gus Van Sant.

The film was produced on a modest budget yet became a box-office and critical success, winning two Academy Awards—Best Supporting Actor for Robin Williams and Best Original Screenplay for Damon and Affleck.

The Legendary Line: “Son of a bitch. He stole my line.”

The ending of Good Will Hunting is often celebrated not just for its emotional resolution, but for the serendipitous genius of Robin Williams’ unscripted final words: “Son of a bitch. He stole my line.” This moment has since become cinema legend, providing a perfect, subtle punchline to the deep relationship woven between Williams’ Sean Maguire and Matt Damon’s Will Hunting.

The Story Behind the Iconic Ending

As Matt Damon vividly recalled, the filming of the last scene—where Sean finds Will’s note in his mailbox—was marked by Robin Williams’ improvisational energy:

“Robin would open the door and come out and find the letter, and I was right next to Gus Van Sant, next to the camera. I would say—because we wanted [it to look like] Robin heard my voice—‘Sean, if the professor calls about that job, tell him I’m sorry. I had to go see about a girl.’ So I’d say that,” Damon explained. “And what was scripted was that he just takes a moment and realizes I’m gone. But in true Robin fashion, we did like 60 takes. We just left the camera rolling… and he did something different every single time. I remember when he said, ‘Son of a bitch, he stole my line,’ I grabbed Gus’s shoulders, and I felt him tense up. We both knew. We were like, ‘holy shit, what a line; how did we not think of that?’”

Ben Affleck, tongue-in-cheek, later chimed in: “Just like we planned it,” highlighting that while the film’s emotional trajectory was carefully constructed, Williams’ improvisational gift brought an unexpected—and unmatched—closure.

What Makes the Line So Powerful?

The brilliance, as detailed by critics and fans alike, lies in how Williams’ ad-lib encapsulates Sean’s journey. Throughout the film, Sean teaches Will about love, sacrifice, and the courage to change. The line is a callback to Sean’s own story, where he missed Game 6 of the 1975 World Series to “go see about a girl”—his late wife. In the end, when Will disappears to pursue love, it’s Sean who’s left with an unfillable silence, expressed not with bitterness, but with a rueful, loving admiration.

As ScreenRant’s breakdown observes: “Williams saying ‘Son of a bitch. He stole my line’ is a swift and complete way to wrap up the relationship between Will and Sean, but also to indicate the impact that Sean had on Will throughout the film.” The improvised line not only reflects Sean’s mentorship but also demonstrates Will’s growth—a full-circle moment where the student honors the mentor by living out the very lesson he was taught.

Perspective from Set and Legacy

Director Gus Van Sant and the crew immediately understood the magic of the improvised line. Damon described grabbing “Gus’s shoulders” as soon as Williams said it, both of them realizing they had struck gold. The laughter and emotion visible on set were authentic; even crew members were swept up in the spontaneity of the moment. As various commentators note, “It’s a simple, heartwarming ending, made even more poignant by the fact that Williams improvised it, and in his delivery gave the movie one of its finest moments. If you’re not grinning ear-to-ear watching it, chances are you’re not human.”

Williams’ improvisations weren’t limited to the final scene: his performance, full of unscripted warmth (such as the famous “wife farting” anecdote), repeatedly disarmed Matt Damon and even disrupted filming with laughter. These departures from the script, rather than being distractions, injected a lived-in authenticity that shaped the movie’s most memorable moments.

Damon and Affleck’s Reflections

Both Matt Damon and Ben Affleck have spoken with reverence about how the ending unfolded. Damon called the ad lib “the perfect ending” and noted that both he and Van Sant were immediately convinced. Affleck quipped, “That was great…Just like we planned it,” fully aware that such filmmaking magic can’t truly be manufactured—sometimes, it just happens when the right people trust each other deeply to try, and try, and try again, until something truly memorable is born.

Conclusion

The unscripted nature of “Son of a bitch. He stole my line” underscores how the greatest movie moments can emerge from genuine collaboration and trust. Williams’ intuitive understanding of his character—and of the film’s heart—turned a routine scene into a legendary one, celebrated for decades by film lovers and scholars alike. If this was a really interesting fact, please check out an interesting story in regard to mark ruffalo brain tumor

“That was great. Obviously, the whole movie was leading to that line, and clearly, we thought this whole thing out.” — Matt Damon

Three Very Interesting Facts

• Script Test: Damon & Affleck added a graphic scene in the first draft to see if Hollywood execs actually read it—those who didn’t mention it, hadn’t!
• Skylar’s Name: Skylar was named after Damon’s then-girlfriend, Skylar Satenstein. Only one original scene made the film unchanged: Will’s first meeting with Sean.
• Casting Battle: Studios wanted Brad Pitt and Leonardo DiCaprio, but Damon & Affleck fought to play Will and Chuckie themselves.