Weaver was born Susan Alexandra Weaver in New York City, the daughter of Elizabeth Inglis, an English former actress, and the NBC television executive Sylvester "Pat" L. Weaver, an American of Scottish decent. Her uncle, Doodles Weaver, was a comedian and actor.

She began using the name "Sigourney Weaver" in 1963, aged fourteen, after a minor character in F. Scott Fitzgerald's The Great Gatsby.

Weaver attended the Ethel Walker School, a prep school in Simsbury, Connecticut and graduated from Stanford University. She earned an MFA at Yale Drama, where she appeared in the chorus of a production of Aristophanes' "The Frogs" and as one of a mob of Roman soldiers in another production as well as, later, in original plays by friend and classmate Christopher Durang. She later appeared in the 1981 off-Broadway production of his comedy Beyond Therapy.

Although Weaver has played a number of critically acclaimed roles in movies like Gorillas in the Mist, The Ice Storm, Dave, and The Year of Living Dangerously, she is best known for her appearances as Warrant Lieutenant Ellen Ripley in the blockbuster "Alien" movie franchise. Her first appearance as Ripley was in Ridley Scott's 1979 film Alien. She reprised the role in three sequels, Aliens, Alien³, and Alien Resurrection. She was nominated for a Best Actress Academy Award for portraying Ripley in Aliens. Ripley was a breakthrough role: the first female action hero. She also starred in two films in 1988, receiving Academy Award nominations for her roles as Katherine Parker in Working Girl and as naturalist Dian Fossey in Gorillas in the Mist. She lost to Geena Davis and Jodie Foster, respectively. In addition to her Academy Awards nomination for Aliens, Weaver has received two other nominations in her career. This makes Weaver one of only eleven actors and actresses to have received two nominations in the same year.

Weaver also has done voice work in television and film. She had a guest role in the Futurama episode "Love and Rocket" in February 2002, playing the female Planet Express Ship. In 2006 she was the narrator for the American version of the Emmy Award-winning series Planet Earth. In 2008 Weaver was featured as a voice in the Pixar Animation Studios and Disney release, WALL•E. She will also voice a narrating role in another computer animated film, The Tale of Despereaux based on the novel by Kate DiCamillo set for release December 2008.

Weaver is notable for her stature, standing six feet tall.

Weaver has been married to film-maker Jim Simpson since 1 October 1984. They have one daughter Charlotte Simpson, who was born 13 April 1990.

After making Gorillas in the Mist, she became a supporter of The Dian Fossey Gorilla Fund and is now the DFGFI's honorary chairperson. Weaver is an environmentalist.In October 2006 she drew international attention through a news conference at the start of a United Nations General Assembly policy deliberation. She outlined the widespread threat to ocean habitats posed by deep-sea trawling, an industrial method for harvesting fish. She also narrated the American version of the BBC/Discovery Channel show Planet Earth, which focuses on the wonders of our world.

On April 8, 2008, she hosted the annual gala of the Trickle Up Program, a non-profit organization focusing on those in extreme poverty, mainly women and the disabled, in the Rainbow Room.

Sigourney Weaver's Photos