The Artificial or Synthetic Alien is a myth in Grand Theft Auto: Vice City. It's also considered a vague Easter egg by the myth hunting community and a texture by skeptics.
The Synthetic Alien is an artificial structure on the sets of the fake Moon landing, which parodies a real conspiracy theory based on the Apollo 8 Moon landings. The Alien is technically a texture that represents a humanoid or four-legged animal, similar to a polar bear, it’s grayish in color with a set of wide eyes. Players have formed a theory claiming that the Alien is a reference to Buzz Aldrin’s claim of sighting Aliens/UFOs on the moon but this hasn’t received official confirmation and the mystery consisting of the Alien texture still remains unsolved but the texture is bears a strong resemblance to reported alien structures and beings on planets and moons around the solar system and particular the Moon. However, it can be a result of detailed textures giving the impression of a humanoid.