In older GTAs
- Grand Theft Auto: San Andreas - Reptilian aliens are spoken of by some pedestrians and the Area 69 base intercom mentions an alien body during the mission there. According to the Epsilon Program, aliens are present on Earth.
- Grand Theft Auto IV; Grand Theft Auto: The Ballad of Gay Tony and Grand Theft Auto:The Lost and Damned - Some pedestrians (mostly the homeless ones) ramble about aliens.
Their bodies are similar to the Vortigaunts from the Half Life series, while their elongated head is reminiscent of the Xenomorphs from the Alien franchise. They have green skin, large crescent-shaped heads, and large mouths with big teeth.
The mission guides the player to drive ahead over the railroads but instead, turn right and go under the bridge, stop the car, get out, and the player will notice that there's a frozen alien in the river.
Aliens also appear during the mission Franklin and Lamar, where an alien movie, Republican Space Rangers is being filmed. They are actually not aliens but people costumed into aliens while the movie casting takes place, and they could be more or less an Easter Egg. At the same time, Franklin and Lamar are racing through the studio at high speeds. Not hitting any of the alien-dressed actors will count for the 100% mission score, checking the "We come in peace" box.
Playing the mission as Michael will trigger a hallucination after smoking pot. Michael's vision and hearing become blurred and the world around him appears to be in a haze. He is suddenly hefting a minigun as aliens begin to appear all around him. Michael must defeat the aliens without dying himself.
Michael goes with Jimmy to a Burger Shot to score weed and a "special drink" from his dealer who works there. On their way back home, Michael experiences the onset of a psychedelic trip after taking a sip of Jimmy's ketamine-spiked drink. Jimmy then forces his father out of the Tailgater, and drives off. Michael then hallucinates being surrounded by monkeys, abducted by aliens, and then dropped off midair floating over the city.
The alien frozen under the railway bridge seen in the Prologue is still there in this mission.
As a method of transportation the aliens use UFOs, or referred to popularly as "flying saucers" or "flying discs". One appears during the mission Did Somebody Say Yoga?, which is used to do experiments on human beings. A sunken UFO can be found at the north of the map at the bottom of the sea. Also, after achieving 100% Completion, a UFO can be seen on top of Mount Chiliad. Oddly, it has "FIB" written on it, which might mean that the agency knows about their existence and even managed to build an UFO by themselves. Different looking UFOs appear in the sky, high above Fort Zancudo and Sandy Shores.
- The aliens' appearance, particularly their elongated skull, is an obvious reference to the Xenomorph from the Alien film franchise.
- The aliens' presence is likely both a tribute to the aliens in Grand Theft Auto: San Andreas and a reference to the Zin race in the rival Saints Row franchise.
- Barry, the man who gives Michael weed in Grass Roots. refers to the aliens as "monsters" (The fact that Trevor hallucinates about clowns instead indicates the "monsters" might vary depending on the person).
- A movie called "Los Santos 2020" features an alien.
- It is possible to look at the alien in the mission Bury the Hatchet. To do this, drive to the rail tracks. After the train has passed, drive on the rails, and then jump onto the river. You cannot fail the mission if you get out of the vehicle, but you will if you go too far from it.
- Other Aliens are mentioned in the game, partially the Anunnaki, Greys and Reptilians.