There's been a fair bit of variety in the aliens seen on screen over the years, from little green men to little grey men to big black xenomorphs with acid for blood (Alien), googly-eyed friendly E.T. and creatures with bodies made entirely of water (The Abyss). Which do you think has been the coolest looking movie alien?
There are so many great aliens to choose from! I think I'd have to go with Stargate, I loved the alien technology and Ra was just cool, even with limited special effects.