Protagonist
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Character Role Analysis
Ripley
Today, we know Ripley is the protagonist before we even watch the movie in the same way we know Norman Bates has some momma drama going on. The cult of personality around these characters has turned them into full-fledged pop culture icons. In Ripley's case, she has become the quintessential sci-fi action heroine.
But in 1979, first-time audiences didn't know going in that Ripley was the protagonist. For the first half of the movie, you might think that Kane or Dallas would eventually be the protagonist. In the second half, all of the human characters are in conflict with the same antagonist, the alien. (Well, except Ash but we'll get to him in a second.)
So what makes Ripley stand out as the protagonist? While we want to see all of the characters survive—they're likeable in their gruff way—she's the character we want to see succeed because she has the right combo of action, intelligence, compassion, and no-nonsense awesomeness. In other words, we all want to imagine that, if we were stuck on an alien-infested spacecraft, we'd be Ripley.