Although it may not have reached the critical mass of Star Trek or Star Wars, the Alien franchise has maintained a considerable fandom in pop culture. To be fair, it is a bit easier to cosplay as a Vulcan than it is to craft a convincing xenomorph costume—although it's insanely awesome when done right.
Online, the fandom is dedicated to dissecting every aspect of the film, both on and off the screen. If you're the chronicler type, then you've found your people. For example, Xenopedia is a wiki site dedicated to all things Alien, Predator, and Alien versus Predator, whereas the Alien Anthology wiki stays within its Alien roots.
Strange Shapes is an excellent fan blog that features some amazing original articles researching the history of the films and their production. The articles about Dan O'Bannon's struggles with writing Alien as well as the wacky ideas David Giler and Walter Hill came up with in their many, many rewrites are especially fascinating. Or if you're looking for more interaction within your fandom, Reddit's LV426 has got your back.
Offline, the fans have kept the Alien franchise alive in every medium imaginable. Alien related video games have come out for every system imaginable. (We're not afraid to admit that we spent many an unproductive Saturday morning blasting the creatures on our SNES.) Then there have been the books, graphic novels, fan made films, and, of course, an active crochet community.
Perhaps most surprising, academics have been pumping out academic papers since day one. More than 35 years later, they're still finding new ways to decipher the story and symbols of Scott's 1979 film and its sequels. Writing for Slate, Tom Shone has produced an excellent overview this cottage industry if you're interested. (How could you not be?)
All this is basically to say, if you love Alien and you love anything else, chances are the fandom has brought the two together at some point. Again, Alien crochet is a thing.