Se7en began production between his two other films, headed by David Fincher as the director and starring Morgan Freeman, Brad Pitt and Kevin Spacey. At one point during production — what would later become a recurring theme throughout Walker's career, the studio proposed several changes, deeming it too dark for its target audience; both Fincher and Freeman backed Walker's original script, and it eventually went unchanged. The film was met with critical acclaim and enormous box office success, earning $327,311,859 worldwide. It would allow Walker to make a name for himself in the movie industry, as well as make stars of then-relatively unknown actors Brad Pitt and Kevin Spacey.
However, Walker would not earn another film credit to his name for another four years, though he penned several uncredited rewrites during this period, including The Game (on which he again worked with David Fincher) and Paul W.S. Anderson's Event Horizon. In 1999, Walker's 8MM finally saw the light of day, having been sold by him for a reported $1.25 million. Once again, the film's production encountered concerns regarding the dark subject matter, and the studio asked Walker to lighten the film's tone. With Joel Schumacher as director, Walker felt a rewrite would no longer be needed. But as it turned out, Schumacher supported the studio and made changes of his own, leading to a much-publicized fallout between the two, with Walker virtually disowning the film and walking away from the set. He refused to even watch the film, which became a critical and box-office disaster.
Walker found other success in 1999, as he penned an uncredited rewrites to the critical hits Stir of Echoes and Fight Club, now considered a cult classic. Walker's adaptation of Washington Irving's short story "The Legend of Sleepy Hollow" also wrapped up production as Sleepy Hollow, directed by Tim Burton. While Burton admired Walker's original script, he hired the famed playwright and Academy Award-winning screenwriter Tom Stoppard to tone down the violence. The film, starring Johnny Depp, was still a box office and critical success.
Since the mid-1990s, Walker wrote several screenplays that were never greenlit or have yet to go into production, such as a script for a movie starring the superhero Silver Surfer, a version of X-Men (2000; his script was written in 1994), and a film tentatively titled Batman vs. Superman. The latter film was set to go into production, but Warner Bros. opted to revive their franchises separately, and so the script was shelved. After the announcement and subsequent successes of Batman Begins and Superman Returns, the film seemed to be shelved permanently, though Wolfgang Petersen, who was due to direct the feature, has continued to express his interest in the project.
Most recently, Walker wrote the screenplay for The Wolf Man, a remake of the Universal Studios classic. The remake, which is directed by Joe Johnston and stars Benicio del Toro in the title role, is aimed for a 2009 release.