It became clear how much that performance touched the people of Boston, where the film is set, when fans paid tribute to Robin by writing his famous lines around the bench he sat on with Matt Damon.
Check out the pics (above) to see them all.
Sometimes it's not until seeing all those lines again that you feel the weight of this loss to Hollywood, and the art of film.
But fans aren't the only ones in mourning. Robin's Good Will Hunting co-star Minnie Driver tweeted: