Aaron Stampler is the main villain of the 1996 movie Primal Fear.
He was portrayed by actor Edward Norton.
He begins as an altar boy for the Archbishop of Chicago. After the Archbishop forces Aaron into sexual activities, he brutally stabs him. Martin Vail gladly takes his case and sees him as a boy scout rather than a killer. He also says to Vail that he loses time when he's very stressed out.
After looking into and discovering things about the case, especially that civic leaders in power are and were involved in corruption and that a Nathaniel Hawthorne book was underlined describing somebody, who is two-faced, he asks Stampler if he underlined that book, which he says he didn't. Then later Vail finds a video tape in Archbishop Rushman's apartment, which shows Archbishop Rushman forcing Stampler and, a woman, Linda, to engage in sexual activity. Vail confronts Stampler and finds out Aaron has multiple personality disorder. Although Vail originally doesn't want to change the plea knowing that it would be problematic and that insanity is hard to prove, he and Stampler decide to use this so-called, multiple personality disorder, to win the case and sure enough they do so.
Vail tells him the verdict is, he will stay at a mental hospital until he's cured. Then Stampler tells Vail to tell Venable, Vail's ex-lover and prosecutor of Aaron's case, that he apologizes for her neck because he attacked her earlier in court and then Vail asks if Aaron loses time then how does he know about her neck. Aaron reveals at the end that he's been lying and faking it and manipulated them all and killed Linda and the archbishop for fun and of his own free will.