Matt Damon Will Hunting Robin Williams Sean Maguire Ben Affleck Chuckie Sullivan Stellan Skarsgård Gerald Lambeau Minnie Driver Skylar Casey Affleck Morgan O'Mally Cole Hauser Billy McBride Vik Sahay MIT Student Alison Folland MIT Student Scott William Winters Clark Philip Williams Head Custodian Patrick O'Donnell Assistant Custodian Kevin Rushton Courtroom Guard George Plimpton Psychologist Jessica Morton Bunker Hill Student Richard Fitzpatrick Timmy Chris Britton Executive #2 David Eisner Executive #3 Bruce Hunter NSA Agent James Allodi Security Guard Michael Arthur Reunion Guest (uncredited) Christian Harmony Student (uncredited) Harmony Korine Hervé (uncredited) Daniel Olsen MIT Student (uncredited)