Robin Williams 'had to be funny to survive', says Good Will Hunting costar Stellan Skarsgård

Skarsgård says Williams’ constant humour on the Good Will Hunting set was more than comedic instinct, it was survival

Late comedy icon Robin Williams brought more than just laughs to the set of Good Will Hunting, he brought a deeply personal coping mechanism, according to his costar Stellan Skarsgård, who recently reflected on working alongside him.

Skarsgård, who played the stern math professor opposite Williams’ beloved therapist Sean Maguire, said the Oscar-winning actor’s constant humor was not just for entertainment but a vital part of who he was.

The Swedish actor explained that Williams’ instinct to joke and improvise seemed to come from a need to keep going, even in difficult moments, recalling that the star “had to be funny to survive.”

On set, that energy translated into a lively, often unpredictable environment. Williams was known for his spontaneous impressions and rapid-fire improvisations, frequently transforming straightforward scenes into extended comedic riffs.

His playful approach could catch fellow actors off guard, but it also created a collaborative, joyful atmosphere that became a defining part of the film’s production.

Skarsgård has previously shared how Williams’ improvisational style sometimes left him momentarily stunned, especially as he was still getting used to working in American productions at the time. But the humor was never mean-spirited, it was inclusive, warm, and a reminder of Williams’ extraordinary ability to connect with people through laughter.

While Williams’ performance in Good Will Hunting earned him an Academy Award and remains one of his most celebrated dramatic roles, those who worked with him continue to remember the emotional depth behind the comedy. For Skarsgård, that balance between humor and vulnerability defined Williams’ legacy, both on and off screen.