The part of Aaron Stampler was widely seen as a career making role and was pursued by many young actors. Matt Damon has said that he chased the role desperately, having previously missed out on a part in Dead Poet's Society. After being passed over yet again, he and Ben Affleck decided that the chances of another great part coming along, going through the ranks of known actors before being "tossed to the wolves to fight over", were so low that they had to do something about it. The result was the script for Good Will Hunting which helped launch both their careers.
Both Wil Wheaton and Leonardo DiCaprio turned down the part of Aaron Stampler. Wheaton turned down the role because he did not want to put off his acting school, and when his manager urged him to take the role anyway, he told him, "It is like Luke Skywalker when Yoda told him not to go and save his friends, but to stay on Dagobah and learn to be a Jedi instead. Luke didn't listen to him and that's why he never became a true Jedi master." Later, Wheaton regretted turning this role down, saying that this was a crucial factor why his career never got to be a successful one.
Leonardo DiCaprio turned down the role of Aaron Stampler because he was exhausted from a demanding shooting schedule on What's Eating Gilbert Grape.