Clearly, Michelle Williams has never aspired to be an "It girl," because the 25-year-old invariably gravitates toward unconventional roles. A Montana native, she was always an original, graduating from high school at 15, then legally emancipating herself from her parents. She landed a role on Dawson's Creek as a big-city blonde who teaches the kids of Capeside the facts of life. After taking a turn toward the commercial abyss with Halloween H20: 20 Years Later, she soon redeemed herself with a slew of art films, including The Station Agent and Imaginary Heroes. Williams validates her independent credo once again in Brokeback Mountain, the new film based on Annie Proulx's cult classic. Set in 1963 Wyoming, it concerns two cowboys—played by Heath Ledger and Jake Gyllenhaal—whose friendship, initially innocent and unassuming, develops into a romance they can never fully pursue or abandon. As Ledger's wife, Williams is racked when she uncovers the secret four years into their marriage. "Michelle was the first to audition for the role, but it was obvious," says director Ang Lee. "She is very special because of her ability to make you believe." In real life, however, Williams went for a happier ending. She and Ledger began dating on the set, and this month she is expecting their baby girl. "Heath kept asking about her schedule when we started filming," Lee says. "His caring went beyond that of a leading man."