Though the role of Ripley was originally designed for Veronica Cartwright (who ultimately played the doomed Lambert), scouts for director Ridley Scott saw Weaver working off-Broadway and felt she would be perfect for the part. The actress' take on the character was laced with a subtlety that made her a new kind of female action hero: Intelligent, resourceful, and unconsciously sexy, Weaver's Ripley was a woman with the guts to master her fear in order to take on a terrifying unknown enemy. Alien proved to be one of the year's biggest hits and put Weaver on Hollywood's A-list, though she would not reprise her character for another seven years. In between, she worked to prove her versatility, playing solid dramatic roles in Eyewitness (1981) and The Year of Living Dangerously (1982), while letting a more playful side show as a cellist who channels a fearsome demon in Ghostbusters (1984).

In 1986, Aliens burst into the theater, even gorier and more rip-roaring than its predecessor. This time, Weaver focused more on the maternal side of her character, which only served to make her tougher than ever. Her unforgettable performance was honored with a Best Actress Oscar nomination, and was followed up by Weaver's similarly haunting portrayal of doomed naturalist/animal rights activist Diane Fossey in Gorillas in the Mist (1988). The role won Weaver her second Best Actress Oscar nomination, and that same year, she received yet another Oscar nomination -- this time for Best Supporting Actress -- for her deliciously poisonous portrayal of Melanie Griffith's boss in Working Girl.

After 1992's Alien 3, Weaver had her next big hit playing President Kevin Kline's lonely wife in the bittersweet romantic comedy Dave (1993). She then gave a gripping performance as a rape/torture victim who faces down the man who may or may not have been her tormentor in Roman Polanski's moody thriller Death and the Maiden (1994). During the latter half of the decade, Weaver appeared in Alien Resurrection -- perhaps the most poorly received installment of the series -- but increasingly surfaced in offbeat roles such as the coolly fragile Janey in Ang Lee's The Ice Storm and the psychotic, wicked Queen in the adult-oriented HBO production The Grimm Brothers' Snow White (both 1997). In 1999, she starred in the sci-fi spoof Galaxy Quest, making fun of her image as a sci-fi goddess while continuing to prove her remarkable versatility.

Weaver's first high-profile project of the new millenium saw her swindling Ray Liotta and Gene Hackman as a sexy con-woman teamed up with Jennifer Love Hewitt. Already into her fifties, Weaver proved she still possessed plenty of sex-appeal even alongside a substantially younger starlet like Hewitt. She played up her sultry side some more in the well-received 2002 indie-comedy Tadpole, but changed gears a bit in 2003, playing a villain in the family sleeper hit Holes.

In 2004, Weaver could be seen as part of the ensemble cast in M. Night Shyamalan's summer thriller The Village.

Weaver has been married to stage director Jim Simpson since 1984. When not appearing in films, she continues to be active in theater.