The Unidentified Alien was one of three alien beings who decided to visit Earth in the year 2340 after receiving the message of peace sent by Professor Von Ziflin using his Radio Spectrum Voltage Pacifier.
Before the Unidentified Alien and his traveling companions Zorgon and Nexor arrived, their Alien Spaceship encountered Prime Evil, who managed to take control of the space vehicle and marooned all three of them on a dangerous, uninhabited Asteroid.
Just before their supplies and oxygen ran out, the three aliens were found by the Ghostbusters and Futura, who had borrowed the spaceship from Prime Evil's ghosts. The Unidentified Alien was the second to be rescued, being carried into the ship by Jake Kong Jr..
Alghough Zorgon had grown weary of meeting any more Earthlings and refused to set foot on Earth or help the Ghostbusters in defeating Prime Evil, Nexor managed to convince Zorgon that there was still good in mankind and to lend the Ghostbusters a hand. The Unidentified Alien remained silent on the subject.
After defeating Prime Evil, Zorgon and the other two aliens finally met the President of the World Federation in greeting. Before the Ghostbusters left to return to their own time, all three of the aliens autographed Tracy the Gorilla's Baseball Bat, which the Ghostbusters proudly mounted on a wall at Ghost Command.
This alien has no lines and his name is never spoken during the episode. He did write his name on Tracy's Baseball Bat, but unfortunately it remains unclear what exact pronounciation of this alien writing would be.
Unidentified Alien first appeared in the episode That's No Alien.