This feature on Ridley Scott’s Alien and the franchise it launched was originally published as part of a package on the most beloved villains in science fiction. It has been updated and republished to celebrate Alienreturning to movie theaters for an anniversary run.

By the time the Xenomorph officially shows up in Ridley Scott’s 1979 classic Alien, the audience has already watched it evolve from foreboding egg to suffocating face-hugger to a tiny, pale critter that’s ripped its way out of John Hurt’s bloody torso. That last scene, destined to show up on Scariest Horror Movie Moments lists until the end of time, cements many of the big conceptual horror movie fears that made Alien famous — the terror of the unknown, the danger lurking both outside and within us, and the anxiety around intercourse, pregnancy, and forced birth.