Unsurprisingly, the lead character of Ripley was written as a man, and, moreover, Ridley Scott flirted with the notion of killing Ripley off during the film’s third act. Eventually taking the opposite approach on both accounts, Scott found himself in a state of panic, as the production was merely three weeks away from principal photography and the only piece of his cast still missing was the woman who’d embody Ripley.
After an extensive audition process, and the anxiety that 20th Century Fox would can his ass if he didn’t pick an actress in time for the production’s rapidly approaching start date, Scott narrowed his field of vision down to two suggestions, courtesy of casting director Mary Goldberg: Meryl Streep, a hot up-and-comer at the time who had Hollywood’s elite buzzing from her work in 1978’s The Deer Hunter, and an unknown off-Broadway stage performer named Sigourney Weaver.
At the time, Streep was the obvious first choice, but there was one problem: the actress’ actor husband, the massively respected John Cazale (The Godfather, Dog Day Afternoon, The Deer Hunter), had recently passed away from lung cancer (in March ’78).
All involved with Alien felt it’d be in poor taste to proposition Streep with their project in her time of mourning, so Weaver, as the studio brass nervously waited, was brought aboard the Nostromo set to test for the part. A few boardroom meetings, and a humble salary of $30,000 later, and Weaver was officially Ripley.