The Greys (also known as Zetas or Reticulians after the Reticuli star system) are the type of intelligent extraterrestrial life that appears most commonly in modern conspiracy theories, particularly UFO conspiracy theories and other UFO-related paranormal phenomena, especially the abduction phenomenon. They also appear in some science fiction and in the mythos of the Raelian movement.

Greys have largely replaced "little green men" as the stereotypical extraterrestrial of popular culture.

Many movies today that include extraterrestrial life most often use the Grey alien. You'll see them in movies such as "Signs" and "Independance Day". The alien life portrayed in these movies use the Grey alien as a model.