Merry Andrew wrote:
I'm not sure if it's the most plausible alien, but for me the most realistically chilling was Alien. The sets of the space-ship were certainly plausible.
The original Alien was actually my third choice. Of course, any time a more highly specialized organism is depicted, the level of plausibility (on a purely statistical basis) goes proportionally down.
My second Choice was John Carpenter's version of The Thing. Even though this movie was designed to be a Horror film, the idea behind the Thing, a relatively simple organism which infects and then duplicates its hosts, seems plausible.
Body Snatchers, Puppet Masters and Invasion use similar ideas, but they also incorporate the concept of a hive-mind super intelligence bent on political dominance, whereas The Thing and Alien represented more basic biological imperatives (reproduction and survival).