What do you think the Alien actually is?

I don't suscribe to the notion of how they were created according to Ridley Scott's concepts for the last two films, like any animal or species in existence, it is a product of evolution, and each animal always seems to correspond to the evolvement of the mankind and what it requires for survival or guidance. Alien had to be a product of an eco-system that requires 1000 times more resilience and protection than that on Earth, that means the substances like he amount of acid the creature could produce had to be a lot more common on the planet and in increased doses, the consciousness that created such life spread around on its planet had to very predatory, far far more than anytime in Earth's known history. Alien film can present very real scenario though, it is all perfectly possible such a creature does exist in the universe, or existed at one time.