Born September 9, 1980 in small-town Kalispell, Montana and raised there until she was ten, Williams started acting after her family moved to San Diego. Beginning with roles in community theatre productions, she was soon shuttling back and forth to Los Angeles for auditions. Williams made her film debut in 1994 with Lassie, and then had a small but memorable part as the young version of the nubile and bloodthirsty alien in Species (1995). After the dismal and virtually unseen Timemaster (1995), Williams moved on to more auspicious fare with Jocelyn Moorhouse's A Thousand Acres (1997). Williams was cast as Michelle Pfeiffer's daughter, and the film's small-town setting must have given her some context for her next role, that of Jenn in Dawson's Creek. The show, which premiered in January of 1998, gave Williams her break-out role, and in short time she was besieged with movie offers and a stream of interviews.

Williams' first film to exploit her newfound Dawson's fame was Halloween: H2O (1998), in which she starred opposite Jamie Lee Curtis. The film opened to poor reviews but a strong box office performance, and paved the way for her to star in future films, including 1999's Dick. The film, which looks at the Watergate scandal from the point of view of two teenage girls (played by Williams and Kirsten Dunst), provided Williams with a chance to expand her range beyond the constraints of her Dawson's Creek character, something she will no doubt be able to continue in the future if her career continues on such a positive track. The first two years of the new millennuim found Williams popularity growing, and roles in such films as Perfume (2001), Me Without You (2002) and Prozac Nation (2003) found her establishing a film career that seemed to even surpass the success she enjoyed on Dawson's Creek.